Bitbucket blocks AWS CodeConnections app with "You can only install for a team"

[Steve Anger]

I'm trying to connect a Bitbucket Cloud repository to AWS via AWS CodeConnections. When I reach the "Install a new app" step, Bitbucket immediately returns:

"You can only install for a team. You must be an admin for a team to install AWS CodeStar. Create a team or contact your team admin to begin installation."

No workspace-selection ("Authorize for") prompt appears — the error shows instead. The Bitbucket authorize URL reached is:

https://bitbucket.org/site/addons/authorize?addon_key=aws-codestar&redirect_uri=https%3A%2F%2Fcodestar-connections.webhooks.aws%2Fredirect

My account is a workspace administrator (member of the admin user group) and a confirmed direct member in the workspace User directory. There is only one workspace in the account. The original workspace owner reproduces the identical error with their own account.

MFA and IP filtering are not enabled.

I seem to have exhausted everything I can try on my end. Is there any way to check on Bitbucket's end why the connection is not being authorized?