Please read Tom's answer here: https://gvectors.com/forum/official-wpforo-addons-official-wpforo-memberpress-integration/group-plugin-tells-me-i-have-to-have-wpforo-installed-and-activated-and-i-do/#post-42616

You should install the Groups plugin before purchasing this addon.

I get this error message: Sorry, but wpForo - Groups Plugin Integration addon requires the wpForo and Groups plugins to be installed and activated.

But wpForo is Activated as allways

I installed wpForo - Groups Plugin Integration again but can't activate it.