If the Add on explorer isn't working, download the web installer from "MathWorks.com" and use it!
Before installing, make sure to check the compatibility with your system and the release version of MATLAB you are using.
Additionally, you can refer to this MATLAB Answer post which addresses similar installation issues with Add-Ons:https://in.mathworks.com/matlabcentral/answers/478990-unable-to-install-add-on
Hope this helps!
