I don’t quite understand what you mean with “the need to sign in with a different password to get onto the website for ‘enabling’ purposes escaped my attention. How do I deal with that issue?”.
AxCrypt (the app! not the web!) does require you to to sign in – but not to the web site. It is the same password, but you do not need to use the web site at all.
If the file was originally encrypted with a different password than used to sign in to AxCrypt (the app! not the web!), then AxCrypt will ask again for the file password.
When I write “Sign in/out to AxCrypt” above, I mean to the desktop app – not the web! Forget the web for now.