There is currently no limit to the number of users you can assign to your account. Each subscription plan comes with a pre-assigned limit but you can add additional users. Check the standard plans on the Pricing page for additional information on the number of users on each plan.
You may add as many user logins assiged to your account as you need by adding a User Bundle. There are bundled options that allow you to easily add as many users as required to meet your team needs.