Probably the same as any other online service; wait for DMCA takedown requests, prepare for lawsuits and be prepared to pay copyright holders or hand over gains to law enforcement.
Of course, that could be prevented if they manually check and verify ownership of every submission.
What about illegal content like CSAM? That would be far more serious than just a DMCA, personally content like that would be my first concern running this type of business.
Of course, that could be prevented if they manually check and verify ownership of every submission.