From my personal point of view, it would better to place NASM directory in C:/FW, to avoid spoiling root directory C:/ and use
set NASM_PREFIX=C:\FW\NASM\
BTW it's also would be useful to mention that "Nasm" directory from downloaded archive contains only text file with directions how to download NASM but not "nasm.exe" itself. It's not obvious thing.
There is some problem. I got: !!! WARNING !!! NASM_PREFIX environment variable is not set Attempting to build modules that require NASM will fail.
It happens because on page https://gitpitch.com/tianocore-training/Platform_Build_Win_Emulator_Lab/master#/17 one of environment variables setup was missed: set NASM_PREFIX=C:\NASM\ Please add.
From my personal point of view, it would better to place NASM directory in C:/FW, to avoid spoiling root directory C:/ and use set NASM_PREFIX=C:\FW\NASM\
BTW it's also would be useful to mention that "Nasm" directory from downloaded archive contains only text file with directions how to download NASM but not "nasm.exe" itself. It's not obvious thing.