NBU installation is exactly the same on VM as on physical.
Please take note of recommendations and limitations over here:
Statement of Support for NetBackup 7.x in a Virtual Environment: http://www.symantec.com/docs/TECH127089
Not sure what exactly is greyed out?
If you have a Windows master server, you need to follow this link:
NB_7.6.0.4.winnt.x64.exe provides fixes for NetBackup (tm) 7.6[.0.1] on x64 Windows server and clients.
www.symantec.com/docs/TECH223735
In TECH223735, click on the 'Attachments' link for patch download.
See attached screenshot.
Oh! For base NBU 7.6 (7.6.0.1) software, start here:
Master Download List : http://www.symantec.com/docs/TECH65429
You will find a link that will tell you how to obtain a serial # for download from FileConnect:
To obtain NetBackup 7.6 GA (7.6.0.1) installation media: http://www.symantec.com/docs/TECH205704
The serial number can also be found on your licensing certificate.
