To add users to your account, you must first make sure you have enough licenses registered under your account. You can easily check how many licenses you have on the Billing page. To add licenses, simply click the arrows (see screenshot below) until you have reached the number of user licenses you need. The adjustments to your billing will be pro-rata, respective to your billing term, for the additional users.
You can add or remove users within your teams:
- Switch to the specific team account.
- Select "Teams" in the menu.
- Scroll down a little bit, now the team members will be visible.
- Invite new members by adding their email address.
- Remove existing members by clicking on the remove button.
Repeat the above if you have multiple team accounts.
To upgrade your number of licenses have a look here: Upgrade your licences.