1. Run 7-Zip Auto-Extracter named NetworkAddonMod Setup 32 SFX.exe.
2. Select the folder in which to decompress the installer (the default will be the same folder as the Auto-Extracter).
3. Go to that folder and run NetworkAddonMod Setup 32.exe, which is the actual installer for NAM 32.
WHY THE EXTRA STEP?
Using the 7-Zip Auto-Extracter on top of the installer has allowed the NAM Team to further shrink the file size of the download (down to 238MB), while also allowing the installer itself to run much faster than the NAM 31.x series installers.
Note that 7-Zip is NOT required to use the 7-Zip Auto-Extractor. Just run it like a normal program.
BUT NOTHING IS SHOWING UP IN GAME!
There's three possibilities here.
1. You did not complete all the necessary steps to install the mod. Simply unzipping the package to your Plugins, or just running the SFX file will not install the NAM to your Plugins.
2. You got a corrupt download. This happens from time to time, and is an issue between your internet connection and the server load, not an issue with the download itself. In this case, re-download the mod. It's possible that one of our other official mirrors may get along better with your internet connection, so it may be worthwhile to try another site.
The only three English-language sites that are authorized to distribute the NAM are ModDB (https://www.moddb.com), SC4 Devotion (http://www.sc4devotion.com), and Simtropolis (http://www.simtropolis.com). Downloads from other sites are not supported.
3. You selected the "Traffic Simulator Only" option in the installer. All this will do is install the NAM's traffic simulator plugin, which improves pathfinding and includes the option to change capacity levels, and will skip over all other addons to the transportation system that are included in the NAM.
WHERE TO GET HELP
The NAM Team is a small volunteer development team (and is presently smaller than in years past). Usually, we only have one developer checking the ModDB comments every once and awhile, so if you're really desperate to get technical support, your best bet is to head to the major SC4 forums. The NAM Team is officially based out of SC4 Devotion (http://www.sc4devotion.com), but also has a considerable presence on Simtropolis (http://www.simtropolis.com). Outside of the team itself, there are many other experienced users around who can usually point you in the right direction with any NAM issues you might have.