This is a bugfix version. We recommend this version if you use several organizations. There was a bug that don't load the organization specific settings if you switch the organization.
A full list of all new features and bugfixes can be found in our issue tracker!
We recommend you to read our announcements for version 4.0 if you have not done before.
If you are new to Admidio and want to install it on your webpage than the following wikipage could help: Install Admidio
The following wiki pages maybe interesting on an Update: Update Admidio