Cannot activate options, checkboxes disabled

After installing and activating APCu Manager there is a banner saying “APCu Manager has been correctly installed.”.

So, I go to the settings page to activate the object cache, but all the checkboxes are disabled and cannot be clicked. What could be the reason for that? Perhaps a conflict with another caching plugin? I have “Autoptimize” and “WP Super Cache” (by Automattic) installed.

Thank you in advance for your assistance!

Sascha