SSRS User does not have required permissions

When we try to open "Report Server/Report Manager" URL (as an user), we may get the below error message.

Error Message:
Report Manager:
User 'admin-PC\admin' does not have required permissions. Verify that sufficient permissions have been granted and Windows User account Control (UAC) restriction have been addressed.

Report Server:
The permissions granted to user 'admin-PC\admin' are insufficient for performing this operation. (rsAccessDenied) Get Online Help.

Reason:
If the Administrator is not assigned the access permissions to the User/Group, then that specific User/Group cannot access the URL's.

Solution:
Click on the below link

SSRS Role Assignment OR Manage User Access

Not Able to See the Report Builder and Site Settings