Unable to add existing DocuSign Administrator in Apps Launcher User Management (MAX_MEMBERS_EXCEEDED)

We're migrating from the legacy DocuSign for Salesforce package to the new DocuSign eSignature for Salesforce.

The migration guide says DocuSign Administrators are not migrated, so we're trying to add them again through Apps Launcher → User Management.

The user is already:

• An active DocuSign Administrator (DocuSign Account and Salesforce(DocuSign Legacy App))

However, when adding the user as an Administrator in User Management, we get:

Failed to add DocuSign membership for user:
The maximum number of members for the account has been exceeded.

My question is:

If the user already exists in the connected DocuSign account, shouldn't Apps Launcher map the existing user instead of trying to create a new membership? Has anyone encountered this during migration?