Deactivation caused cache and website error

First of all, I am not tech savvy, I have just been tasked with keeping up with the company site. I have zero coding abilities.

I had a critical site error that require me to deactivate and then reactivate all my plugins to resolve. Upon reactivating WP Super Cache I recieved the following error message”

Warning! You may not be allowed to use this plugin on your site.
The file /home/dh_7ufnqt/lagun.com/wp-content/advanced-cache.php was created by another plugin or by your system administrator. Please examine the file carefully by FTP or SSH and consult your hosting documentation. 

I’m not really sure what this means or why I’m seeing it. I have no other caching plugin, and have been using this plugin for the past month without any issues.