The Ubiquiti UAPs (indoor and outdoor) will mesh automatically if they all share the same SSID (and of course have to be on the same IP subnet). To set the best path: You have to do that manually in the UniFi management software
In resonse to customer question:
Author: George Hardesty
Our testing was excellent for the Ubiquiti OutdoorAPs. We’re finalizing our proposal and will be purchasing more of them from you. My only question is how to make them mesh automatically for best path? I only see how look and see manually which is best path and them connect them. (Using the UniFi management software).