If your goal is to develop simple scripts that can be loaded onto the BLOCKS hardware and run independently from a host application, you should read about The LittleFoot Language and Getting started with BLOCKS CODE. BLOCKS CODE is designed to work seemlessly with BLOCKS hardware and allow you to compile and upload LittleFoot scripts to BLOCKS instantly. More details are provided in The LittleFoot Language and Example LittleFoot Scripts sections.
You can also download the standalone BLOCKS SDK from GitHub here. This includes the roli_blocks_basics JUCE module and the other JUCE modules required for the SDK. Using this version of the SDK is much more complicated but may be more suitable for integrating BLOCKS into an existing application. More details are provided in The standalone BLOCKS SDK and Example BLOCKS Integrations sections.
The BLOCKS SDK uses the JUCE framework, which can be obtained from GitHub here. Whilst you don't need to know anything about JUCE, it will probably be worthwhile reading some JUCE tutorials, which can be found here.
Learn how to connect BLOCKS in the Connecting BLOCKS section or start discovering BLOCKS in your applications by jumping to the Discovering BLOCKS section.