Imaging Engine cannot access the output folder location, though it can be accessed from the file explorer. Both Automation Engine and Imaging Engine BGMD services running with bgsystem user account should either be on local bgsystem or domain bgsystem.
You should be able to find the mismatch by doing the following:
On Automation Engine Server and Imaging Engine server:
Go to Services and double-click BGMD services.
In the BGMD Properties window, go to the Log On tab
This account field will display the account on which this service is running.
If your servers are on domain, both BGMD services should be running on domain bgsystem user. You should be able to change from the local bgsystem user to the domain bgsystem user by following these steps:
Click Browse... beside This account field.
Select your domain from the Directory and click OK.
Type BGSYSTEM and click Check Names (you should be able to see the bgsystem entry as in the below screenshot).
Enter the bgsystem default password. Click Apply and then OK.