To make sure this theme works you can do the following.
1st BACKUP DB AND FTP!!!!!!
Go to FTP:
1. When accessing htaccess or wpconfig make sure opening settings changes are 664 instead of 644 to reduce issues
This will install the plugin for sure. Follow the pup-up steps.
2. The hide backend part
If you can not enter the hide-back-end changed URL, got to you back-uped .htaccess file and look for the RewriteRule part where you see your changed url e.g. RewriteRule ^EMAMPLE-login/?$ /wp-login.php?f552sgsggs [R,L].
Change all the [R,L] to [QSA,L]. After that copy from this line till above </IfModule>.
Paste this in the renew .htaccess of iTheme security before # END Hide Backend.
After this you can enter your website again and the GoogleAuthentication will also work again.
Maybe I left somethig out. Correct me if I.m wrong