Chat support is available through the UniFi controller. The controller is free, so this means support is free. There is also a very active community and forum on Ubiquiti's website, and also on Reddit and other third-party communities.
Several times now I have encountered an issue and reached out to chat support, only to be linked up with an actual UniFi engineer. This has led to resolutions for any issue I've encountered. It's clear that Ubiquiti is interested in helping customers -- they recognize that fixing an issue encountered by a user not only helps that user, but also makes their UniFi product line more useful to all.