Zoom requires the app developer to have credits and require a participant-initiated REST start to target an invited participant who has joined.
Zoom staff has confirmed that Basic hosts are supported when the RTMS developer account has Developer Pack entitlement. Error 2308 is not necessarily caused by Development mode, so verify that the initiating participant was explicitly added to the invitation and has joined. Publication matters when customers must install or authorize the app because App Review is required before external users can add it. OAuth scopes do not override customer controls. Admins can disable Share realtime meeting content with apps at account, group, or user level, and hosts can still require approval or deny access.
Recall.ai is a Zoom RTMS Preferred Partner, with further RTMS integration support available through Recall.ai.