CMSIS repo for MCU+ SDK is a stripped-down version of the ARM CMSIS5 software layer taking mostly the math functions using ARM intrinsics, from the original repository. This is used mostly in certain application examples and benchmark examples. Please refer to the original CMSIS repo here
This repo is meant to be used with MCU+ SDK repo for building certain application examples. Refer MCU+ SDK Core repository for more details regarding the MCU+ SDK.