Problem with wpForo Premium Plugin Activation / Setup

I installed wpForo and the Advanced Attachments plugin. I have the license key, but the board is still disabled.

Everything was checked:
– Forum loads correctly
– Slugs are aligned
– WordPress 6.8.1
– PHP 8.2.22
– Hosting confirmed there are no blocks and mod_security was disabled

Question:
How do I activate the plugin using the license key?

Thanks.