In AB Projects there's no sign-up form and no email invite. If you're in the Microsoft Teams channel a project is linked to, you become a project member automatically — you don't even have to open the app first.
How you become a member
- Be in the linked Teams channel. That's the whole requirement. If you're not in the channel, ask a channel owner to add you in Teams.
- Wait for the next roster sync — it runs when any channel member opens the AB Projects tab and is throttled to about once per hour per project, so you're usually picked up within the hour.
- You're added as a Member, with your Microsoft identity registered — so you can immediately be assigned tasks and @mentioned in comments. (Member is the standard working role; the full set is in Role-Based Access Control.)
In a hurry? A project Owner or Admin can also add you on the spot from the Team page — see Adding or Removing Members.
What opening the tab actually does
Opening the tab isn't what makes you a member — but it's how you start using AB Projects: seeing and working your tasks, commenting, and switching views. Your first visit signs you in with Microsoft SSO (single sign-on — the same account you use in Teams; a work or school account, not a personal one) and sets up your session and language. And if you're the first person in the channel to open the tab, your visit triggers the roster sync that brings everyone else in.
Someone's missing from the assignee or mention picker?
When a name doesn't appear in a task's Assignee or Mention picker, it's almost always one of these:
| Likely cause | Fix |
|---|---|
| The roster hasn't synced since they joined the channel | Have any channel member open the AB Projects tab to trigger a sync, then refresh. Remember the sync is throttled to roughly once an hour. |
| They're not in the linked Teams channel | Add them to the channel in Microsoft Teams; they'll be picked up on the next sync. |
| They were removed from the project but are still in the channel | They'll be re-added as Member on the next sync automatically — see Adding or Removing Members. |
| They're a Viewer | Viewers can't be assigned tasks by design. An Owner or Admin can promote them to Member — see Role-Based Access Control. |
One nuance: the Mention picker only lists members with a Teams identity, because a mention is delivered as a real Teams @mention — see Task Comments and Mentions.
In short: get into the channel and the rest happens by itself — membership, assignability, and mentions all follow from the Teams roster.