I'm a bit unclear on the original purpose of the camp at Westerbork.
From the Holocaust Encyclopedia: "The Dutch government established a camp at Westerbork in October 1939 to intern Jewish refugees who had entered the Netherlands illegally."
From the Jewish Virtual Library: "This camp had been opened by the Dutch authorities during the summer 1939 in order to receive the Jewish refugees coming from Germany."
I can't quite tell if it was built as a way to help the refugees by giving them a place to live. Or if it was more of an internment camp. The two articles use the words "intern" vs. "receive". Maybe that's where my confusion comes from.
Between 1933 when Hitler came to power and 1940 when the Netherlands were occupied by the Nazis, large numbers of Jewish refugees attempted to gain safety in the Netherlands and other nearby European countries. Because they did not know that war would break out, it was for many a more achievable way of leaving Germany than attempting to get a visa to countries in the Americas, the British Mandate Palestine, or the UK. Many German Jews instead escaped to Western Europe, mainly France and the Netherlands. Westerbork was initially built by the Dutch in 1939, before the German occupation of the Netherlands, as a place to house German Jewish refugees who had escaped Nazi Germany but entered the Netherlands illegally. The fate of the prisoners at this point usually depended on whether they were able to organize their visas. Many got visas to enter the Netherlands, some were deported, some were kept until the Dutch government could figure out what to do with them.
From the German invasion of the Netherlands in May, 1940 through 1941 it remained a small refugee camp, but was of course now under the control of the Germans, as they had control of the Dutch government. However, it was still staffed by Dutch guards at this point and had a very small prisoner population.
The construction of killing centers in Eastern Poland began in late 1941 and the Operation Reinhard death camps were operational by 1942. Most Dutch Jews were murdered in Sobibor and Auschwitz between 1942-1945. Early in 1942, as plans for the Final Solution were being organized, the Germans expanded the camp at Westerbork, and by July of 1942 the German security police, assisted by the SS and Dutch MPs took control of the camp and turned it from a refugee camp into a transit camp under the command of Erich Deppner. The camp would act as an organizing point for shipping Jews East to their deaths in Sobibor and Auschwitz. The summer of 1942 was the height of killing in Sobibor, and the height of deportation and murder of Dutch Jews.
https://encyclopedia.ushmm.org/content/en/article/westerbork
https://www.yadvashem.org/odot_pdf/Microsoft%20Word%20-%205952.pdf
Peter Tammes. "Jewish Immigrants in the Netherlands during the Nazi Occupation." The Journal of Interdisciplinary History 37, no. 4 (2007): 543-62. http://www.jstor.org/stable/4139477.