Hi @Martin Richmond ,
Based on my research, Office 365 App for Business is not contained Teams service. For your reference, we've included this master table of the subscriptions that enable users for Microsoft Teams.
If you just use Teams to join the meeting, you can join the meeting as anonymous users in the web client. With anonymous join, anyone can join the meeting as an anonymous user by clicking the link in the meeting invitation. For your reference:
Skype for Business can be licensed as a stand-alone product or as part of the Office 365 application suite.
It is available as an on-premises server, known as Skype for Business Server, or a cloud-based service, known as Skype for Business Online
If the response is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.