As of February 2021, Apple started enforcing additional authentication for all users when signing in to App Store Connect by making two-factor authentication a requirement (see: https://support.apple.com/en-gb/HT204915). This extra layer of security for your Apple ID helps ensure that you’re the only person who can access your account.
This means that for us to be able to publish apps to your Apple Developer Account on your behalf we can no longer use your username and password for your Apple Developer Account, but instead, we have to use the official App Store Connect API which does not have the same two-factor authentication requirements.
The App Store Connect API allows you to automate the tasks you perform on the Apple Developer website and in App Store Connect (see: https://developer.apple.com/documentation/appstoreconnectapi).
We have integrated with the API already, however, we require a few things from you to authorize us to communicate with the API on your behalf. Kindly follow the following steps to grant us access:
Generate an API Key
To generate keys, you must have an Admin account in App Store Connect.
To generate an API key to use with the App Store Connect API, log in to App Store Connect.
Select Users and Access, and then select the API Keys tab.
If are prompted to request access, click on the Request Access button and accept the license agreement, else skip to step 3 below.
Click Generate API Key or the Add (+) button.
Enter a name for the key. The name is for your reference only and is not part of the key itself.
Under Access, select the "Admin" role for the key.
Email email@example.com and include the Key ID, Issuer ID, and API Key attachment (AuthKey.p8 file).
NOTE: You MUST download this file immediately. You cannot retrieve it later.
The new key's name, Key ID, Issuer ID, a Download API Key link, and other information appears on the page: