Hi, Wendy. Sorry you are running into issues.
It’s hard to tell exactly what is going on without more information. If you see a specific error on the screen or in your PHP and MySQL error logs when trying to add a level, it can give us a hint to what is going wrong.
In general, when this has happened before it was because the Database tables weren’t created properly. You can use something like PHPMyAdmin to make sure our DB tables were created in your blog DB. You can try to create them manually. Here is our setup.sql script (note that the table prefixes will need to be changed if your DB prefix is not wp_) https://github.com/strangerstudios/paid-memberships-pro/blob/dev/includes/setup.sql
I noticed that PMPro is not active on the URL you shared. Maybe you deactivated it while working on the site. Or make sure you are really talking about PMPro if you were trying out a few membership plugins ??
If you can give us more information, we can try to help. Or if you are sure you want to use PMPro and post to our paid member forums we can get more information from you to access your site and fix things for you. https://www.paidmembershipspro.com/pricing/
