Backup both Mac and PC to same drive?

I am having a problem with my Mac Mini backing up to my 2T MyCloud drive. The first time it managed succesfully, then I backed up my PC laptop. Now my Mac crashes or just fails to backup. I’m suspecting it’s related to the laptop structing the drive to a format the Mac is incompatible with. Any suggestions?

The PC is not going to reformat the drive – a mac might though and prepare it for Time Machine.  The devices require different formats on the drive though. and I believe that exFAT format works with both, but I am not sure of what you should do here.