You can add team members by clicking on the profile option from the top right corner and selecting the members section.
If you are on the 1x Plan, an upgrade to the 2x Plan is necessary to accommodate an additional team member. Similarly, the 3x Plan permits up to three team members, and so forth.
To add more members to your account, go to your subscription page and click on upgrade Plan. From here, you can increase the slider to 2x or 3x and select the plan after which you share an invite with the person.