Here is a list of directories the 64-bit installer will try to create, from monitoring a fresh install using Process Monitor:
C:\Program Files (x86)\InstallShield Installation Information
C:\Program Files (x86)\InstallShield Installation Information{5D4F167D-CCC8-413E-A6EE-F2FABBBBF50D}
C:\Program Files\GPSoftware
C:\Program Files\GPSoftware\Directory Opus
C:\Program Files\GPSoftware\Directory Opus\Help
C:\Program Files\GPSoftware\Directory Opus\Images
C:\Program Files\GPSoftware\Directory Opus\Language
C:\Program Files\GPSoftware\Directory Opus\Themes
C:\Program Files\GPSoftware\Directory Opus\VFSPlugins
C:\Program Files\GPSoftware\Directory Opus\Viewers
C:\Program Files\GPSoftware\Directory Opus\x86
C:\Program Files\GPSoftware\Directory Opus\x86\VFSPlugins
C:\Program Files\GPSoftware\Directory Opus\x86\Viewers
C:\ProgramData\GPSoftware\Directory Opus\Buttons
C:\ProgramData\GPSoftware\Directory Opus\Global Data
C:\ProgramData\GPSoftware\Directory Opus\Icons
C:\ProgramData\Microsoft\Windows\Start Menu\Programs\GPSoftware
C:\ProgramData\Microsoft\Windows\Start Menu\Programs\GPSoftware\Directory Opus
C:\Users\Tester\AppData\Local\Microsoft\Windows\Caches
C:\Users\Tester\AppData\Local\Temp{4A64385E-5AB7-4D05-859E-0F14D2E5DFB2}
C:\Users\Tester\AppData\Local\Temp{840F8578-474D-4596-A6C2-B18FF646AF3B}
C:\Users\Tester\AppData\Local\Temp{BB052865-5F6E-4D4F-B030-4774761F5590}
C:\Users\Tester\AppData\Local\Temp{BB052865-5F6E-4D4F-B030-4774761F5590}{5D4F167D-CCC8-413E-A6EE-F2FABBBBF50D}
C:\Users\Tester\AppData\Local\Temp{F3FD7CBF-F704-4438-84E1-8353E6136935}
The C:\Users\Tester\AppData\Local\Temp paths will vary depending on your system, but should be under the whatever the Temp directory for the Administrator account is. (If you're logged in as an admin then you can type /temp in Opus to find it. If you're using over-the-shoulder elevation to run the installer as a completely separate account, you can use an administrator command prompt to find out what %TEMP% points to, which is usually the right path unless the env-vars are wrong.)
It's possible that some of the GUIDs (long numbers in {...}) will also vary, but check that similar directories can be created below the Temp folder, for example.
Some of the folders will (normally) already exist, which is fine, but for any folder that doesn't exist, check that the administrator account has permission to create it.
It's also possible that InstallShield is giving a misleading error message, so if checking that you can create all those directories doesn't turn up anything, it may be worth using Process Monitor (if you're familiar with it) to see which operations the installer attempts which fail.
Some of the suggestions under Problems Installing Opus may also be worth a try, although none of them match these exact symptoms.