This community does have have a small list of consultants who are willing to do paid work for helping people integrate Let's Encrypt.
I don't know if any of them support Unifi, though, which is in some ways its own world. (I use Unifi switches and wireless access points myself for my home network, but I haven't yet explored getting a "real" certificate on the controller, and I use a first-generation CloudKey, so I'm not sure I would be much help either.)