I need to spend some time on it but I purchased two Omada APs to pair with my OpenWRT router thinking roaming would just work with mostly Apple devices. That didn’t happen. I’m hoping some of this article applies and I can improve the situation a bit.
For Omada devices, you need a "Controller". You can run the Omada Controller software on an existing computer, get one of their controller devices, or use their cloud-based service, which should be free at your scale.