To perform workplace join for android devices, you can do so by :
1. Download Azure Authenticator from Google Play Store :- https://play.google.com/store/apps/details?id=com.azure.authenticator&hl=en
2. Once downloaded the app, open the app. The Azure Authenticator app not only provide code for MFA, it also possible to use for workplace join.
3. Click on menu (top, 3 line). Click on Add work account
4. Key in your Azure authentication to enable your device join and access organization resources.