You can install OWA directly from a branch on Github. Here are the steps:

1. Clone the repository: git clone https://github.com/Open-Web-Analytics/Open-Web-Analytics.git
2. Choose a branch or tag: git checkout the-branch-name
3. Run Composer to fetch all dependencies: composer install or if you are installing into a production environment composer install --no-dev --optimize-autoloader --prefer-dist --no-interaction
4. Run npm run build to build the javascript packages from source. See OWA's npm build process documentation for more info.

For more information on installing composer in your environment see: Composer install docs

For more information about how the OWA Git repository is structured see: OWA Git and Github

Binary distributions for each release can be found on the Releases page. The binary distribution is includes all the 3rd party dependancies required by the release. Use this binary if you do not want to deal with composer and just want a fully packaged distribution.