Build
Android
Launch Android Studio
In the top menu, select Build -> Generate signed Bundle or APK
Select the required build type and click Next
Select Keystore and key, enter passwords and click Next
Check the boxes for Jar signature and Full APK Signature and click Finish
Note
To publish the build to Play Market, use Android App Bundle
iOS
Launch XCode
Go to project settings on the Capabilities & Signature tab
Specify the required profile and certificate
In the XCode top menu, select Build -> Generic iOS device
In the XCode top menu, select Build -> Archive
Follow the prompts in the modal window
Select the latest build in the newly opened Organizer modal window
Click Upload
Follow the prompts in the modal window