You can add new user groups by clicking the hamburger icon on the upper-left of the page, and select Groups under User Access.
Group Administrator：Group administrators can create, update, and suspend users in the user group. They can also add sheets to a Group Tab or make design changes to the sheets under a Group Tab.
Group Tabs：To add a tab as Group Tab, enter the tab's URL slug in the Group Tabs field (e.g. /forms1, as it appears in the last part of the tab’s URL). Separate each tab by commas when there are multiple tabs.
You can quickly add a new user group under Design Mode while you are setting up access rights. Go to Form Settings > Access Rights, and click on "Add User Group" under the list of existing user groups.