When installation is over, you will be prompted to choose an existing Ryzom installation if detected or to specify another directory.
If you miss too many files, it will download with bittorrent or wget the whole data from current Windows installer and uncompress them for you.
If you need to update your data, it will use rsync to patch data to last version.
To launch Ryzom, simply go in your Applications -> Games menu and click on Ryzom.