Only a few Android mobile devices are able to run Premiere Rush, per the program's system requirements.
Welcome to the Rush community. As of now, Premiere Rush is available on selected mobile devices. However, our product team is actively working on device expansion in the list of supported devices.
Here's a link that directs you to the Rush system requirements: https://helpx.adobe.com/in/premiere-rush/system-requirements.html#Upgradeyouroperatingsystem
Let us know if you have any questions.