If regarding an OT server, it's quite simple:
If you call your donations anything else but "Donations", you are quite literally making money off something cipsoft created. This is illegal.
This will also result in CIPsoft sueing your ass off the second they find out about it.
So either you call your donations "Donations" or you pay a hefty lawsuit bill of around 100,000 Euros or more to CIPsoft GmBH. Your choice.
Have donation on their server isn't illegal, cuz CipSoft hasn't Item Shop or SMS shop, They have paypal and Card Credits, so far as i know its legal.
and i know tibia is Copyright, but people use their own map and ofc how hell can they sue you, their is like 000.00.1% that they sue you, since they just have warn Classictibia.com