The Mckap shelf will appear with the McKap button on it.

Click the button to launch McKap.

On the first launch, choose the license option.

Follow the usage instructions here https://mckap.com/help/

The installer that ran when you downloaded this plug-in from Autodesk App Store has already installed the plug-in.

Windows only: To uninstall this plug-in, Simply rerun the installer by downloading it again from Autodesk App Store, and selecting the 'Uninstall' button, or you can uninstall it from 'Control Panel\Programs\Programs and Features' (Windows 7/8.1/10), just as you would uninstall any other application from your system. The panel on the Plug-ins tab will not be removed until Maya is restarted.

For installation instructions, please refer to  https://mckap.com/help/

For more information please refer to https://mckap.com/