A bug fix is available for 3.0.0 version. This version is a stable release version 3.0.1. Install it only if you experience some problems with 3.0.0. A migrate process will be asked, choose the last one, event if in this version, there is no database change compared to 3.0.0

Also note that a featured release 3.1.0 will be soon available as a beta.

You should find download links into download area: http://www.dolibarr.org/downloads/cat_view/62-stables-versions