Cannot add user to database during custom installation of Enterprise Console version 4 database

Issue
During a custom installation of the Enterprise Console database on your server, when attempting to add a user to the database, you see the following error message:

Could not add new user 'tester1' to server '\\[servername]'
Cannot find the network path.

Known to affect the following Sophos products and versions
Enterprise Console, version 4

What to do

During the installation of the Enterprise Console database, you are asked to enter the Windows user groups that will have administrative rights over the database. You cannot add individual user accounts. Add the user to an existing group in Windows, or create a new group for the user, and then restart the installation.