Admin cannot install plugins | WordPress.org

I have been having issues with my site. errors occurred. I began to deactivate Plugins, to identify the issue. The plugins disappeared. I deleted existing files of the plugin which was still in the wp-content, reinstalled, and on activation, “this plugin does not exist” comes up. And the same for any new plugins. Any help would be greatly appreaciated.

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