Verge3D can run on top of Blender, an open source 3D modeling and animation suite, which should be installed first (both versions 2.79b and 2.80 are supported). You can download Blender for free from the official website.
Download Verge3D and unpack it to a directory of your choice. Make sure you have enough permissions to read/write in this folder. Installing in a system directory such as "Program Files" is not recommended.
Open Blender and go to "User Preferences" by selecting the corresponding option in the "File" menu.
On the "File" tab, find the "Scripts" field and make it point to the folder in which Verge3D is installed. Click "Save User Settings", close the "User Preferences" window and restart Blender.
Open the "User Preferences" window again and go to the "Add-ons" tab. Find and enable the Verge3D addon, then click "Save User Settings" and close the preferences window.