You can create groups of users to assign projects and tasks just like individual user. 

User having admin role or having wppm_manager or wppm_administrator role can create usergroup. To assign wppm_manager or wppm_admin capability, you can edit wordpress register user and assign role to them.  You can assign any usergroup into project. In tasks, you can only assign usergroups which are assign to their selected project.  When you assign usergroups to project or task all users from that usergroups will get assign to that project or task.

For more details, please follow this link.