Click on one of the Max versions (under “assets” on bottom) and download
Extract the contents of the zip file on your computer, and open the directory corresponding to your 3DS Max version. Finally, make sure 3ds Max is not running, and move all .dll files into the installation directory of 3DS Max (in C:/Programs/Autodesk/3ds Max/bin/assemblies). The next time you will start 3ds Max, the plugin will be automatically launched, and a new tab should appear:
To export your 3DS Max File as GLTF, go to the menu, Babylon->Babylon File Exporter.