v0.1 is the first release of MessagePack for https://modelica.org. The code is still incomplete in that not everything you would want to do with the MessagePack format is supported.
The code should work in all Modelica tools supporting external objects and serves as an example on how to implement an external object for manipulating binary data from within Modelica.
The non-source code archives contain headers and libraries of the C version of MessagePack. If these are already installed on your system, it is possible to use MessagePack using only the source releases.