One account equals one workspace.
This means:
A person can only belong to one account/workspace under a given email address, across the entire Forge Stack.
Anyone being invited to your workspace must create their account through the invite link sent to their email β not by signing up on their own. If they sign up independently, that creates its own separate account and workspace, not a membership in yours.
If someone already created their own workspace on their own, they cannot be invited into your workspace afterward β this isn't something that can be done from the invite flow. In this case, contact support for assistance.
Add Existing User β use this for someone who was previously part of your workspace and was removed. Click Add Existing User to bring them back, instead of sending a new invite.
Add New User β use this for anyone who has never been part of your workspace. This sends an invitation email, and they must use that link to create their account.
From your Forge Account, go to Settings

Click βUsersβ or βUser & Rolesβ

You will see this buttons on the right side of your screen:

If you want to add existing users on your workspace, click βAdd Existing Usersβ. Quick Note: Clicking the Select option with a drop-down button will show you the previous users you would like to add in your workspace. Once selected, click Add user to a workspace.

For New Users, click βAdd new usersβ. You are required to share their active email address to complete the signup and invitation.

On the Pro plan, your Salesforge account is limited to 1 user. Inviting additional teammates requires the Growth plan, which supports multiple/unlimited users. This limit is specific to Salesforge β Mailforge, Primeforge, Warmforge, Leadsforge and Infraforge allow inviting users at no extra cost regardless of plan, since their pricing is based on mailbox slots, not seats.