Are you sure you want to go to an external site to donate a monetary value?
WARNING: Some countries laws may supersede the payment processors policy such as the GDPR and PayPal. While it is highly appreciated to donate, please check with your countries privacy and identity laws regarding privacy of information first. Use at your utmost discretion.
More of a recommendation than an issue, but when I used to write userscripts I took advantage of HTML5's download attribute, which forces the file to download instead of opening in the current window.
http://www.w3schools.com/tags/att_a_download.asp