The Germans facilitated Lenin's return to Russia from Switzerland, as well as the return of a number of other socialists in exile there. However, this was after the February revolution had already happened. The revolution in Petrograd took most of the organised revolutionaries completely by surprise, as they had not expected the Tsar to be overthrown quite so quickly. Many of the leaders of the Bolsheviks, Mensheviks and Socialist Revolutionaries were either in exile or in Siberia. Lenin, Zinoviev and Martov were in Switzerland, Stalin was in Siberia and Trotsky had to take a trip halfway around the world. At one point he was interned along with German merchant sailors in Canada, but eventually released when the Captains complained he was converting their crews to communism.

News of the revolution took a while to reach Switzterland, where there was a large community of other Socialist exiles along with Lenin. Once news had reached him, he resolved to return to Russia as soon as possible. However, he could not easily cross the Eastern Front, and the British and French governments were unlikely to help him return to Russia, where his presence could only destabilise the Provisional Government. A number of schemes to return to England under a false passport were rejected, and eventually passage was negotiated with the Germans. Lenin, Zinoviev and another 29 Bolsheviks and other Socialists boarded the train in Zurich, which travelled through Germany at high speed. Such high priority was given to the train that at one point the Crown Prince was delayed because of its passage. Once at the Baltic Coast, Lenin travelled through Sweden and Finland, arriving in Petrograd on the 3rd of April.

The German Government certainly didn't allow Lenin to return to Russia out of charity. They were fully aware that he would have a destabilising effect on Russia. Lenin was also aware of their thinking, and took advantage of them to secure his return. Once back in Russia, the Germans also probably funded the Bolsheviks. Lenin accepted this money not because he was a German agent, but because he was willing to take any advantage to secure his revolution. Understandably, however, there is some controversy about whether the Germans actually did fund him.

Source:

Catherine Merridale, Lenin on the Train. (2016).