I was trying to join by donating, but I'm getting a 404 error from the web-page after the "remember to use /buy craft" popup, and /donate in game is just telling me "something went wrong" - is this a problem on my end or is the donation system not working atm?

If the in-game donation system is not working then you can go to main page and on the right hand side where it shows the donation's there is a text box where you can input the amount and then make the donation there:)