There are at least three ways to install Scapix:
Make sure you have git lfs:
$ git lfs install Git LFS initialized.
Scapix will be added as dependency repository to your git project.
In your project root execute:
$ git submodule add https://github.com/scapix-com/scapix
$ git clone https://github.com/scapix-com/scapix
Download the following zip file and extract inside