Restoring backup failes

So basically my box was messed up after updating it, so I thought why not try the backup function (like described in the manual). So I set up a new droplet in DO, fresh mailinabox install and tried restoring, however I’m met with the following error:

Any idea what’s causing this? Thinking it might be me trying to restore the wrong files. Looking in the encrypted folder there are lots of different individual files, 3 new ones get added every night at 3a.m., as far as I understand. Which of those am I supposed to restore? I tried all of them, but maybe that’s my problem?

Anyway, thanks for any help in advance!