Is there a rule against/recommendations for an author tipjar?

I've poked around on the forum and saw CHYOA has an overarching subscribestar, but I'm wondering if I can link a 'Buy the author a coffee' or something on my story. I wanted to confirm if that's alright and ask if there's a best way to go about it?
Sorry if this is a duplicate question from elsewhere

 

A tip jar or sth similar for your created content on CHYOA is fine.

 

thanks!