The first user at creation of the WizyEMM console is the Master Account and is a "@gmail.com" email address.
A "@gmail.com" email address is needed because the setup of a WizyEMM account triggers the setup of a Managed Google Play account, which is then linked to your WizyEMM account. Managed Google Play accounts require an "@gmail.com" login. G Suite email addresses are not allowed, since they are already linked to a Google Play account.
It is a best practice to have a dedicated Gmail account (email@example.com), managed by your company and NOT use a personal Gmail address owned by private individuals (as they might leave your organization).
This Master Gmail address:
- will forever be the Master Account of your WizyEMM console
- is the email address which manages your company's Managed Google Play account