How can authenticated users of a site join a group implemented using Groups module? Pre-requisite knowledge:
I am using Group module to implement &quot;Group&quot; functionality on my drupal site similar to what Organic Groups module implements. I have a user role community-leader whose users have been granted the permission (under People &gt; Permissions) - Technology : Create New Group so that they can create new groups of type Technology, but normal authenticated users have not been granted this permission so they cannot create groups.
Group module provides separate permissions on its configuration/overview page under Group Roles. These group roles are for users involved in a particular group. In my case, users who create the group (essentially of Community-leader role or a user-role with higher permissions) are assigned Group-leader role and then there is a Group-member role supposed to be assigned to users who will join the group created thereafter.
For these roles (both Group-leader and Group-member), permissions like Join Group, Request Group Membership, etc. are disabled (no checkbox available instead a 'x' sign is present). I believe this is because since a Group-leader created a group, he automatically joined the group and there is no meaning of these permissions for him.
Note: The above roles (both Group-leader and Group-member) are global group roles, not group-type specific roles.
Problem Statement
An authenticated user on my site is unable to access a particular group's page and thus has no way available to join the group. There is no granular(specific) permission available for this purpose.
Moreover, even Group-leader or Group-member role users cannot access groups other then their own group. How to allow that?
Could someone please guide me on Group Access Control for a better understanding?
Drupal 7


Download and activate Group.
Activate submodules Group add (gadd) and Group node (gnode).
Click on Group that now appears in your menu bar next to Content (/admin/group). This is the main overview for administering Group, here is where new functionality will appear when you activate more submodules.
Go to Group Types, in a tab on the page (/admin/group/type)
Add a group type, you only have to choose a name
Click "edit permissions" (/admin/group/type/manage/partner/permissions)
Activate suitable permissions. "Outsider" are logged in users that are not part of the group. Add at least view and add permissions for one content type for members, and "View group" permission.
Go back to the Groups start page (/admin/group)
Create a new group
Click on your group name, then click Add member
Add some members
Log in as one of those members, go to your account, click the Group tab, click on "view group"
Add some content


Now you have the basics of a group. Users, content, permissions and some ways to interact. Look through the rest of the tabs on all pages you visited, go into the detailed settings screens, activate more submodules, group roles, group permission etc. Extend using the group api hooks. Set up a suitable user interface using standard tools (views, VBO, rules, fields on the group). 

For other settings you can visit following urls :


https://www.drupal.org/node/2711123
https://www.drupal.org/node/2711049
https://www.drupal.org/node/2711119
https://www.youtube.com/watch?v=w2Ol19OzNAQ


Drupal 8 

Watch this video for a excellent and complete use-case configuration. 

Hope this will clear all doubt.