If you have available seat count, you can add a seat by going to Users and clicking +User.
When creating a seat, you do have the ability to automatically send a claim link.
If you do not have available seat count, you must ask an Outreach account manager or email firstname.lastname@example.org for new user seats, both for on-boarding and billing purposes. If you'd like to onboard a new team member, we would be more than happy to help you get setup. Please email us at email@example.com and we'll get you going.