The zip file also contains .png versions
All types each are contained within one .ico file.
To install, simply right click your hammer shortcut and go to properties, then under the Shortcut tab, go to change icon. Browse to the .ico's location and select it. Now you can choose the color and size. If you use small icon sizes, the unpixelated ones will work, and if you use larger icon sizes, the pixelated ones will work better. Just experiment and see which one looks best.
The reason they look pixelated is because they are being resized by windows and alias. The other ones were resized separately to make the anti-alias better.
Previews and credits:
Original Green and Blue HD Icons found here https://spamcan0.deviantart.com/art/Valve-s-Hammer-Editor-Logo-390684131
I just cropped, resized them, and converted them to .ico
TF2M logo cropped out from https://tf2maps.net/downloads/tf2maps-net-steam-workshop-resources.642/
This B1/TF2M logo was made by me.
This one was made by @Pdan4.
This one was made by @Tumbolisu