Bitrix24 comes with free online file sharing server that requires no installation and is ready to use in 30 seconds.
You can also deploy Bitrix24 on premise, install it on your own server and alter source code, if necessary. Regardless if you choose free or paid editions, cloud or self hosted,
you get the same set of features - desktop apps for PC and Mac, mobile apps for iOS and Android, online and offline editing, document management with flexible access rights
and support for GoogleDocs, MS Office Online, MS Office, Pages, Open Office or any other local office suite that you want to use. Active Directory support is available
in the self hosted editions only.
If you want to start using free online file sharing server, this Bitrix24 manual will get you up to speed quickly.
In order to test self hosted (on premise) edition of Bitrix24, you need to download it from here. Please keep in mind that it takes about 1.5 hours to deploy and set it up.
Self hosted Bitrix24 manual is available here.