Plugin No Longer Working

Good day,
I installed and was using this plugin successfully until last week when it completely made my site go haywire. Not only would the plugin not work but my pages disappeared. I had to deactivate it, of course.
I really liked the plugin and was looking forward to purchasing some add-ons I needed to make my subscriptions and logins work easily and smoothly. Now I’m not sure what to do… I am by no means a technical person and I am learning as I go…

The page I need help with: [log in to see the link]