It's free for personal use, but you have to donate a small amount if you want to use it for commercial projects

So it's free like those free trips to Hawaii I'm always getting calls about.

Much clearer if it said ""This wonderful font is free for personal use. For commercial use, a small amount donation is required""

The readme file is better worded

"You may use this version of <font name> for personal use. For commercial use, you need to donate via Pay Pal. <author email address>"

Clearly a purchase and not a donation. The font creator would need to declare that on his/her taxes.

If the donation is required, in exchange for some services, is it still a donation?