The Windows 7 installer does not find the Samsung SSD 960 Pro, because this SSD is not connected via SATA, but via M2.
You can either install Windows on some other disk (preferably also an SSD, but with SATA connection), then connect the Samsung SSD as second disk, install the Samsung Drivers, and finally clone that Windows from the SATA-disk to the M2-SSD.
Or you need to load the Samsung drivers while installing Windows. The rest of this text describes how to do this.
The Windows installer does allow to load drivers before starting the install (on the screen on which it asks "Where do you want to install Windows?").Update:
But Samsung does not offer to download just the driver, only an installer package.
And that installer package refuses to run if it does not find an attached Samsung SSD 960 Pro.
Download the Samsung NVMe driver from
for example (at the time of this writing)
Extract Samsung_NVM_Express_Driver_2.1.exe from that ZIP-file, place it on your desktop.
Download the binaries archive of the WiX toolset
For example (at the time of this writing)
Extract all contents of file wix311-binaries.zip to the directory desktop\wix
run in cmd.exe
wix\dark.exe Samsung_NVM_Express_Driver_2.1.exe -x C:\SamsungExt
msiexec /qb /i Samsung960ProInstaller64.msi
Copy the driver files from C:\Program Files\Samsung to an USB thumb drive.