Hi @DavidAnastasi-13,
You should ensure the license included Microsoft Teams in your organization. Based on my research, the following picture shows the master of table of the subscriptions that enable users for Microsoft Teams, you can refer to the following picture and choose your own license suitable for your environment.
After setting up Microsoft 365 subscription, you can visit the Microsoft 365 admin center at admin.microsoft.com. You can add your own domain to Microsoft 365 and Teams by yourself. For more details about how to create custom domain, you can refer to:
https://practical365.com/microsoft-365/configure-a-custom-domain-in-office-365/
Note: Microsoft is providing this information as a convenience to you. The sites are not controlled by Microsoft. Microsoft cannot make any representations regarding the quality, safety, or suitability of any software or information found there. Please make sure that you completely understand the risk before retrieving any suggestions from the above link.
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