Access Extensions inside your Opencart Store via.
People are having trouble with the Marketplace API thing on the top right corner so here is a solution.
To begin using it for new extensions and themes, you will have to setup your Marketplace API.
First, go to your OpenCart account here.
Then go to Your Stores to register your shop.
This Solution comes to you from
https://isenselabs.com/posts/install-uninstall-extensions-opencart-30
Thank you Mihail Savov.