Client insists on not setting up a my business account for their corp so I'm wondering if there's a way to gain CRA represent a client access to their business account online without them having to create a my business account, themselves?

Trying to search online but it seems the only way to gain access is for them to approve it on their end, which would require them to have a MBA set up. I'm using this link as reference: https://www.canada.ca/en/revenue-agency/services/tax/representative-authorization/how.html . Even using EFILE with a signed business consent form seems like they'll still need to approve online.

Thanks!