Managers can determine which constituents have access to group pages and group content. If Group Page access is set incorrectly and a role or user type has been excluded, users will not be able to view their content.
Similarly, if access has been given but users are unable to view a certain content type (e.g. Photos), the content needs to be enabled.
There are three types of users:
Associated Users are constituents who are tied to the group (e.g. students who are enrolled in a course section)
Special Users are the group managers and content editors
All other constituents belong to Roles (e.g. all parents belong to the Parent role)
Managers can grant Associated Users three different types of access:
List Only. Constituents can view the group name but cannot access the group page or group content
Group Page/Portal Content. Constituents can access the group page and view the group content on the Activity Stream and portal (if in use)
Portal Content Only. Constituents will only be able to view the group content on the portal (if in use)
Managers can grant Special Users and Roles Group Page/Portal Content, or List only access.
Related: How do I set up Group Page Access?