I started with changing the nameservers for the domain, waited a bit more than an hour, then tried the form.
I received the basic "nameservers are not set to" error message (no big deal there as it often takes time to propagate).
I tried the form a bit later and got the error "domain is already part of the free service" (or something similar to that).
I checked the domain (hostang.ga) and sure enough the myownfreehost.net template was active.
Unfortunately, I never received any email (and still haven't... and not in spam folder) so have no credentials to log in.
My best guess is that the first error caused the second error, thus triggering the template setup but not completing
the credentials (I'm assuming with the signup form, there is additional information required once you pass the first screen)