Hi grahamm7,
Thank you for the posting in our forum community.
According to your description, we suppose you cannot access Microsoft Teams resources in your Organization. If so that, for accessing such kind of resources or application in the organization, the Office 365 admin has must assigned
proper Office 365 license to their user. For accessing Microsoft Teams application, the user has must
assigned Microsoft Teams license from Office 365 admin center.
Here is the detailed steps for assigning Microsoft Teams license under Office 365 Business Product license:
Sign in to Office 365 portal > Go to Office 365 Admin Center> under
Users > Active users> select the user, choose edit besides
**Product license (**in new admin look select “Licenses or Apps”tab) > tick Microsoft Teams under Office 365 Business product license for the selected user > Click on Save changes.
For your example reference:

If I misunderstand anything wrong from your above mentioned post, kindly correct me. For better understanding and analysis of some point of situation, I need to collect below information from your side.
1. Could you please provide us detailed information about this “retail outlet”? Is this retail outlet is any member or any guest for your Office 365 tenant organization?
2. Kindly provide us detailed screenshot about “When I try to log on as one of our retail outlets i get the message
Your sign on was successful but does not meet the criteria to access this resource”.
Kindly provide us above information as per your convenient time. We will be very glad for further assistant.
Regards,
Darpan