You download Degoo directly at degoo.com/download.
Degoo will start downloading automatically if you have a supported operating system. If not you will get a list of operating system that Degoo supports and are able to download Degoo to any of these.
After Degoo is downloaded you simply run the downloaded setup file and the installation of Degoo will begin.
You might be asked to allow the setup file to be run. If you're asked - click OK or Run.
The setup will install Degoo automatically. After the installation is complete Degoo will start automatically and you can log in or sign up directly in the software and start backup your files!
See this guide on how to backup your files.