I am facing the same situation I do have something like this:
https://www.example.com
community.example.com
university.example.com
I followed the next instruction from the BB folks:
and does not work. I am almost giving up this.
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As the multisite setup is a single WordPress installation and only has one database meaning you will only need to install the BuddyBoss Theme and have its license activate once through the Network Admin.
As long as your sites are subsites of the Network, then you’ll only need to activate the license of the Theme once.
Just make sure it’s activated on your main site, then proceed to activate the plugin and theme one at a time on your subsites, like you would on your main site.
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Any thoughts?