Many thanks for posting the link.
Those sample files are in a compressed format (.rar) and as you have said will require software such as 7-Zip to extract the archive.
Although some of those files have .TAP, .tap and some have .nc file extensions they are all Text files just the same. When loading Gcode files into Mach3 you have the option to select the particular file extension (.tap, .nc, .ncc, .txt) or, if you prefer just select All Files(*.*).
The individual .tap files within the archive are not, in themselves, compressed so once the .rar archive has been opened / extracted no further decompression of the files is necessary.
Tweakie.