Generate Build & Upload to TestFlight

1. Access the AppMaster.io Studio and click on the three dots icon on your app's card in the Mobile Applications tab.

2. Click "Publish App" to open the Publish Wizard.

3. Make sure that you have selected the right app, select "App Store", and click "Next".

4. Choose the target deployment plan that your app will be run on, and click "Next".

5. Enter you Apple ID and Team ID.

Follow these steps to locate your Team ID:
Log in to Apple’s Developer Center
Once you are logged in, click on Account
Then Membership
Under Membership Information, locate the Team ID field

6. Enter the Key ID, Issuer ID, and API Key file generated in previous steps.

7. Input the App Name and Bundle ID of the new app you created in App Store Connect in previous steps. Also, input the version and build number of your app.

8. Review the information and click "Submit".