More details at https://en.wikipedia.org/wiki/Hartz_concept#Hartz_IV

If you go through the system, you'll be provided housing. It's only if you actively avoid or can't deal with the system that you can end up homeless in Germany. Part of the deal (it's a contract, actually) is having to look for work. If you can't find any, you may be required to accept any kind of job to continue to receive benefits.

Yep, good summary. Just one detail:

> any kind of job

Within limits. People have successfully sued against having to take jobs unreasonably (physical incompatibility, far away from family, etc.).