It’s suppose to automatically detect them via zeroconf, but if its not you can delete .storage/homekit_controller-entity-map and restart HA and it will refetech the config from your hub.
If that doesn’t work then it either doesn’t support the type of device you added or its not visible in the homekit API of your hub. Either way please do raise a GitHub issue for this. GitHub is the best place to get hold of me (the homekit_controller maintainer).