The correct plugin is not on the Unity Asset Store. You need to get it from the official JoiPlay Patreon or their GitHub.
JoiPlay is a powerful Android launcher that allows you to play various PC game engines on your mobile device. While it natively supports popular engines like and Ren'Py , its "deep features" regarding Unity compatibility are often misunderstood because JoiPlay does not use a specific "Unity Plugin" in the same way it does for other engines. Key Insights into JoiPlay & Unity Compatibility unity plugin for joiplay free
While there is frequent discussion among users looking for a way to run Unity games on JoiPlay, . The correct plugin is not on the Unity Asset Store