All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
If this center is a governmental institution run administratively and financially by the government, then you should work there according to the regulations put by the government. In this case, the center works in conformity with the government's regulations and you should not collect donations without the permission of the government.
But if this center is an independent institution and the government is only one of the parties that donate for it, then, it is lawful for you to raise donations and your salary is lawful.
Allah knows best.