I have tried to look this information up on the website and the FAQ section. It says nothing about specific incomes like crowd funding or donations. I think that Galeon is right, maybe someone from Epic could clear this up. They could also make it all a bit more clear to everyone what the “rules” are on the actual page that discusses this.
Just the simple “Once you’ve begun collecting money for your product, you’ll need to track gross revenue and pay a 5% royalty on that amount after the first $3000 per game per calendar quarter.
Royalty payments are due 45 days after the close of each calendar year quarter. After the end of each quarter, you will need to provide the following information.” is not enough (for me atleast) to understand all the rules about this system. That is why I made this thread in the first place, so that people would have 1 place where ALL possible questions about this are asked. 
If any of you have additional information or have original sources about this, then please let us know!