There doesn’t appear to be a way to add a Bluesky account for cross-posting with their ‘E-mail 2FA’ enabled. The 2FA will send you an alphanumeric code in this format: XXXXX-XXXXX. There is not a location, that I can see, to input the code when adding a Bluesky account.
To be clear, I was able to quickly add BlueSky by momentarily turning off 2FA on Bluesky and then re-enabling it after authenticating the account.
Thanks!