Hi Nir,
I've actually managed to donate via my phone and on mobile data, I don't know if it was my laptop or the dodgy Wifi, but now it's done.
There's also a Bitcoin donate link for those interested.
@Pawel - to your initial point you can simply put your Credit Card details in the link (looked safe) or transfer via BTC. If you check other posts on this forum you'll see that Soulseek has been having issues with PayPal.
I don't know where you're based, but if you can get Revolut that's a good and safe option for such payments as you have a Virtual card (attached to your accounts) that you can activate to pay and then deactivate seconds later.