If you’re new to Taiga and would like to invite your team to the platform, you need to do so after you have created a project. Once you have created a project, you can go to SETTINGS>MEMBERS and add them. Invites will be sent by Taiga to all of them to join both Taiga and your project. If you invite team members that are already Taiga users, they will be immediately added to the project and they will get notified as well.
Inviting team members to Taiga requires inviting team members to at least one project where you have ADMIN or OWNER status, that is, you can access the SETTINGS panel for that project. Once they have a valid Taiga user, they can be invited to many other projects and they can use Taiga based on their account type.