For the latest system requirements, visit http://www.adobe.com/go/indesign_systemreqs.
For a list of the latest system requirements for other Creative Cloud products, see http://www.adobe.com/products/creativecloud/tech-specs.html#requirements.
Creative Cloud trials are "try and buy", allowing you to evaluate individual products or editions and then convert the installed trial to a full version. You can convert from a trial to a full version at any time by signing up for a subscription. If you purchase a subscription, make sure that you are online and have logged in with an Adobe ID to start using your full version.
For a list of new features delivered in InDesign 2015.3, see Adobe InDesign CC 2015.3 Release | March 2016.
For general Adobe community, visit https://community.adobe.com.
To find help on topics related to downloading, installing, and getting started with your software, visit http://community.adobe.com/t5/get-started/bd-p/get-started?page=1&sort=latest_replies&filter=all.
For product Help plus community-based instruction, inspiration, and support, visit http://www.adobe.com/go/learn_InDesign_support_en.