@cihomewood this is an older thread, but I'm having the same problem.  How, exactly, did you solve it?  Do you recall what scripts needed to be removed?  I had the forum all set up, and looking great.  I then set up a fictitious registration, and it re-directed me to my login page, which had the same behavior as yours.  I'm on a managed WordPress plan with Ionos.   The login on the WPforo navigation menu opens up the login page that now has the WordPress login as well as an option to login through Ionos, same as your screenshot above.   HELP