First the codes. Please do not transfer any money into my demo account. The sheet records the entire transaction. I had to use an extended code (not script) for that. I will let you guys figure out (so don’t be surprised if my demo below shows exact amount also being asked for). I have given enough clues below!
Here is the code

RESULT
DONATION BUTTON

RESULT
You change the logo by replacing the objects url. The sheet records the transaction which can be followed up with email confirmation by bouncing it to the client. I will let you figure this out
HERE IS A LIVE DEMO : PLEASE DO NOT TRANSFER ANY MONEY!