If you want to use two-factor authentication for Fastlane on Bitrise.io use this step.
Two-Factor Authentication:
The step now supports two-factor authentication.
It will use the Bitrise.io built-in Apple Dev Portal auth feature to connect your Apple Dev Portal account even if the two-factor authentication is enabled for your Apple developer account.
How to connect your developer account to Bitrise.io:
https://devcenter.bitrise.io/getting-started/signing-up/connecting-apple-dev-account
Note:
“2FA will be required to sign in to your Apple Developer account and certificates, identifiers and profiles starting February 27” - https://gadgets.ndtv.com/apps/news/apple-adds-two-factor-authentication-requirement-for-developer-accounts-1993631