I think this might be because in the system path environment variable, your MATLAB installation path appears before the MATLAB runtime path. Move the runtime path up, so that it appears first before any MATLAB installations.
Sometimes you might also encounter a similar error, but the missing directory is actually under the MATLAB Runtime installation directory, i.e. you see something like this:
RuntimeError: Could not find the directory C:\Program Files\MATLAB Runtime\R2019b\toolbox\compiler_sdk\pysdk_py
This is most likely because you have previously installed MATLAB Runtime for running other type of applications, such as standalone executables etc. These are generated with MATLAB Compiler, whereas software libraries, such as Python libraries, are generated with Compiler SDK. Hence, you're missing the Compiler SDK part of the MATLAB Runtime. The solution is to install the full version of MATLAB Runtime, which youc an download from this website, or use the installer file that was most likely generated when the Python library was packaged.
