Plugin does not work – WordPress Multisite configuration

Hi,

i have a WordPress MU installation and the plugin does not work.
Modal box does not appear instead of blocked ad.

I am not able to check the “Flush files” option. It stays unchecked even after i “Save changes”.

I believe the temp folder is not created in the “uploads” dir. What is susposed to be its name?

Thanks

https://www.ads-software.com/plugins/adblock-notify-by-bweb/