Well I missed this, and I’d be willing to bet that many others did too.
I just went to the PlatformIO home page, and navigated to the download page. The only place I saw anything about donation is the small text at the bottom of the page under “About”, and honestly I only found that because I was specifically looking for it.
I think you should make your request for donations much more prominent on the website, so that all visitors understand that this project needs support. Perhaps it could be a more general “How to Support Us” type link that also encourages users to contribute code.