XF doesn't care what the URL is so assuming the DNS has propogated fully, you should be able to log in.
Point 6 of the FAQ details what steps you need to take to ensure emails and links continue to work correctly: https://xenforo.com/community/threads/frequently-asked-questions.5183/#post-180455
I just checked a few invalid URLs on your site and I receive the standard 'Oops! We ran into some problems.' message.
You would need a consistent reproduce case in order to determine what may be causing it.
Members can adjust that setting in their account page: https://xenforo.com/community/account/preferences
For any existing subscribed threads, they just need to unsubscribe from them: https://xenforo.com/community/watched/threads