I tried to enroll as an Apple developer and received this error message with no help or guidance from Apple on resolving it:
Sorry, you can’t enroll at this time. Your Apple ID is already associated with the Account Holder of a membership.
Googling this error message didn't provide any useful information.
Turned out I had once paid for an Apple developer membership a decade ago and forgot about it.
You need to go to https://developer.apple.com/account/. From there, you can renew the account.