This email address is not available for use as an Apple ID. You may already have an Apple ID associated with this address. Please try again or sign in using your existing Apple ID.
The issue that I found was that the email address was being used as an alternate email on an already existing account.
Remove the alternate email or change it, then you will be able to use the email for an Apple ID.
转载请明显位置注明出处：itunesconnect – iTunes Connect错误：“此电子邮件地址不可用作Apple ID。”