mytabs not allowing users to register

i'm having the same exact problem as this guy -https://nulledbb.com/thread-CLOSE-ME-Mytabs-for-mybb

he solved it but never posted the solution. if anyone has ANY idea on steps to fix this i'd greatly appreciate it.

Update that plugin to the last review as far as i known that plugin is deprecated but already there is a new version that fix all those old issues.