Team accounts are considered to be added in 2019. Until then, only single user accounts are offered. If you want to grant others access to your account, you can consider sharing your account login details.
How will team accounts work?
With a team account, you can create multiple user accounts that share the same URLs and screenshots. One user account manages the team account and is in control of payments and invoices. (As this is still a future roadmap feature, the objective or details of team features may change later.)