To invite a new collaborator, click on the red plus sign next to your avatar in your project. Enter the email address of your collaborator into the field and click Invite.
After sending the invite, you can select the level of permissions you wish to grant the person.
The number of people you can invite depends on your Video Editor plan. Collaborators will have their own email and profile in your team account.
Note that project invitations are different from review links. Review links are free and unlimited. The number of project invitations depends on your subscription tier.