I realize that after WW2 the allied powers wanted to make up for the hurt the Germans caused to the Jewish population so they gave them a territory which the Jewish people would then call Israel

This assumption is quite common, but comes with a lot of caveats that should be addressed. Firstly is that Jews had already been moving to and living in Palestine in large numbers for decades at this point. Secondly, the political leaders of this Jewish community had already been engaged in political campaigns, violent insurgency and even open warfare against the British on and off since the 1930s - in what they viewed as a conflict to give the Jewish people a nation state. Although, the Yishuv (and correspondingly, the Haganah) had more or less halted it's anti-British efforts during WW2 - seeing Nazism as a greater enemy than the British - the post-war period saw a return to British-Jewish tensions. Thirdly is that the British Mandate of Palestine was actively in a civil war between the Jewish and Arabic communities by 1947. Many Arabic communities in Palestine also desired national self-determination and there had been multiple anti-British revolts and conflicts in the majority Arabic areas of Palestine in the 20s and 30s. There had also been a great deal of violence and tension between the Jewish and Arabic communities throughout this period - with numerous instances of massacres on both sides. Jewish migration to Palestine, and proposals of a Jewish state, were largely opposed by Arab Palestinians. By 1947 this situation had disintegrated into a conventional civil war between the Jewish and Arabic militias and paramilitary groups.

Fourthly, as you can guess, is that the partition plan was proposed principally to be a solution to this civil war - and as an exit strategy for the British after decades of failed policy - and not as reparations for the Holocaust. The British stridently blocked Jewish migration to Israel at this point of time, without much if any international criticism or comment. The idea that Israel could be a homeland for displaced Jews in post-war Europe, many of whom were still in refugee camps, was largely a fixture in Zionist and pro-Zionist rhetoric. It was less of a priority for British decision makers than arriving at a resolution for the conflict in Palestine.

Fifthly, is that many of the allied and Western powers were frustrated by this process, and its contentiousness, and took policies chiefly to end the conflict - rather than shore up Israel. The US blockaded arms trading and supplies in the region. The American Jewish community was largely pro-Israel, and donated, lobbied and even volunteered to fight for the cause of Israel - but the degree to which their efforts convinced American political leadership on Israel is questionable. The prospective Israeli state's key supporter, at this point in time, was actually Czechoslovakia - whose weapons supplies were crucial to Israel's ability to later fight against the Egyptian, Syrian, Iraqi and Jordanian armies. The USSR at points toyed with the idea of Israel potentially being a counter-balance to Anglo-American influence in the Middle East, and provided some level of diplomatic support for Israel at times.

Sixthly, of course, is that the partition plan - i.e. this - was never actually enacted or enforced. By the end of the war, Israel looked like this. Also worth noting is that the 1947 partition plan prescribed the creation of a state for the Arabic population of Palestine. This didn't happen - either during the war or afterwards. The areas designated to become a Palestinian state in the 1947 plan, that weren't under Israeli control, were occupied by Jordan and Egypt after the war - and have become what we now know as Gaza, the West Bank and East Jerusalem. The borders, and survival, of Israel were largely decided by the successes of the nascent Israeli military and the defeat of Palestinian, Egyptian and Syrian forces - as well as the relative successes of the Jordanians, who had significantly increased their territory in the war, taking the whole of the West Bank and East Jerusalem.

What I don’t understand is how the allied power got that land to give to them? Did they just take it from Palestine?

So to answer this - the territory wasn't really 'given' to Israel by the allied powers. More or less the proposed plan ceded territory to areas which often already had large Jewish populations - sometimes majorities - and which were in many cases already more or less controlled by Jewish militias and political organisations - largely the Haganah. Following the 1948 war, the borders of the nascent state were decided by Israel's military successes.

In essence, a lot of the premises of this question are incorrect. The partition plan was not created by the international community to say sorry for the Holocaust - but was conceived as an end to an ongoing civil war by splitting the British Mandate of Palestine into two nations and conceding to both parties the independence they were fighting for. The partition, regardless, was never enacted and the civil war ended with the Israelis having secured themselves a state and with the remaining territory of the Mandate of Palestine being occupied by Jordan and Egypt.

While you're waiting for an answer to your specific question, I found this excellent comment by, unfortunately, someone who deleted their account, but it explains a lot of the history surrounding this. It goes into some detail, but a quick tl;dr is that it was being administered by the UK since the end of WWI, when the Ottoman Empire fell. (Before that, it was part of the Ottoman Empire, and before that, the Roman Empire, and before that is more than 2,000 years ago.)