Security “Bug”

Hi there,
I install ultimate member 2 times and have to install both times.
What happened is I install it, do all the right configurations, test it, in 2 diferente browsers and everything work fine. But after I log off and when I try to login again I get this “can do the login do to security reasons”.
So I go to my cpanel and delete the ultimate member plugin, and after this I can login in my site.
I did 2 times to be sure it was this plugin.
Anyone have an idea why this happened?

Kind Regard