Teams error message: You don't have access to the ____ org in Teams. Select another org, or contact your admin.

Question

Everyone in my small business is now getting a message "You don't have access to the ____ org in Teams. Select another org, or contact your admin." This is because our "Teams Exploratory", the free version of Teams (Classic), has expired. We want to use the "New" Free version of Teams for all employees. But there is no clear method of doing this. The link (https://support.microsoft.com/en-us/office/switch-from-microsoft-teams-free-classic-to-microsoft-teams-free-4601d413-4419-40a8-8ca3-fe899ccdaa68?culture=en-us&country=US) does not offer informative instructions. This seems to be for personal email accounts, not small businesses with a corporate email.

I am the admin. I have access to all users. We have some employees with 365 Apps for Business on our account. How do I set it up for everyone to use the "New" Teams Free, so they can log in without getting this error message? We do not need the paid version of Teams, we only use it to attend Teams meetings as a guest that others, like our customers, have set up. Thank you.