If I'm not mistaken, though, it's important to note that for non-donators (and people who haven't bought the game on Steam), that amounts to about £10. The "donator features" are automatically triggered and cost 60 Voratun Coins, even if you only donated enough for 50 coins, at which point you'll end up with -10. So you'll need to have a total of 100 coins to actually get the expansion. Unless there's some way to bypass the donator bonus and go straight for the expansion.

...I hope this is made more clear on the page to get the expansion itself. I'd hate to see people get upset that they've paid £5, only to see their account at -10 and be told they need to pay another £5 to get the thing they were after. People are far more likely to assume malice than miscommunication.

You get the same system as everyone else. Go check your Balance.

Yeah, as enzan said, check your balance and link your accounts and you'll get credited 60 coins (and it'll possible be used on the donator status)

You have donated 5€, which is 50 coins. The donator features cost 60 coins (to align with store sales), but sicne I'm nice you are still able to use them.
So you have 50 - 60 coins left :)