If you sign up for Ultimaker Essentials (which is the basic version that is free if you have an Ultimaker Printer), you will get the option to create an organization and you can already share 5 projects with the entire organization.
If you want more finegrained sharing through Teams, you need to have the paid version, as Terri described above.
Note that if you only see "Teams", but not "Organization" in the "Manage" section, you are still on the Personal (home user) version of Digital Factory. If you use your Ultimaker printer in a professional organization, I would strongly recommend to start using Ultimaker Digital Factory Essentials.
Activating your Essentials subscription can be done here: https://ultimaker.com/software/plans
