"User "****\**" doesn't have permissions to access audit data. Contact your audit administrator." error encountered when launching the ApexSQL Audit GUI (4369858)

"User "****\**" doesn't have permissions to access audit data. Contact your audit administrator." error encountered when launching the ApexSQL Audit GUI.

To resolve this issue, first do the following:
1. a) Confirm if your account, “****\********” is indeed a part of Administrators group:
Run Computer Management -> Local Users And Groups -> Groups -> Administrators -> see if the “****\********” is listed there.

b) Check if the same account have sysadmin role on the SQL Server running the ApexSQL Audit CRD:
Run SSMS -> Connect to the SQL Server where you have installed ApexSQL CRD -> Security -> Logins -> select the “****\********” account -> right click -> Properties -> Server Roles -> sysadmin box must be checked.

c) If all the above is good, this means you do have required permissions, then please do the following:
Run the ApexSQL.Audit.Installer.exe as Administrator from the C:\Program Files\ApexSQL\ApexSQL Audit location and use your admin account “****\********” for configuration.

2. If the first approach doesn't resolve the issue, try the following:
a) Create a local account for running Audit, add it to the Administrators group, create a login for it on the SQL Server instance with sysadmin rights, and then use it for running ApexSQL Audit (enter that account in the Credentials field).

b) After the installation is complete, don't start the UI right away (because you are not logged in as the user you assigned for running ApexSQL Audit). While holding SHIFT, right-click on the ApexSQL Audit application icon and select the option Run as different user, or you can just log in on the machine as the newly created user and start the ApexSQL Audit GUI.

3. If the issue still persists, try the following approach: 
a)  Examine the application log files. If the following message is displayed 
“An exception occurred
There is already a listener on IP endpoint 0.0.0.0:64561. This could happen if there is another application already listening on this endpoint or if you have multiple service endpoints in your service host with the same IP endpoint but with incompatible binding configurations.”

This means that the required port is used by some other none-ApexSQL Audit application.
Check if any of SQL Server TCP ports are using either 64561 or 60408 and if yes, change it to default port which in turn allows ApexSQL Audit to use its default ports 64561/60408. Thereafter, retried opening the Audit application and it opened without any issues.

Check the ApexSQL Audit system requirements