https://ryzom.com/?page=page_system_requirements (Storage: 10 GB available space)
To install the game, download the installer at https://ryzom.com/ Ryzom Installer is the new tool to install Ryzom, then configure, manage your profiles and play.
You can use Steam too. When there's an update on the game (server patch), Steam and Mac Users have to wait a little bit to get the newest stuffs.
Regarding the operating system and version, and how the game has been installed, the game can be found on various locations, more on Ryzom location.
For help with problems running the game when your system meets the above system requirements, look at the official forum site, where you can also ask for help from a support representative if you cannot find a solution to your problem.
You can use the Ryzom external chat at https://chat.ryzom.com/ (login with your toon name - more on An issue to log in?)
There's some IRC channel too on freenode.
Ryzom currently supports four different languages; English, German, French, Spanish and Russian.