You can find the add-in under the OTHERS panel in SHWIVEL tab of DESIGN workspace.

For creating gears, you must run this add-in.

The window has default parameters, so you don't need to set them at the start.

Hit the "Ok" button to create the gears.

Change the parameters per your specific requirement and hit "OK" to create the gears. 

Install:

The installer that ran when you downloaded this app/plug-in from Autodesk App Store will start installing the app/plug-in. Or, simply double-click the downloaded installer to install the app/plugin. 

Uninstall:

You can unload the add-in without uninstalling it by clicking the "Stop" button when the add-in is selected in the list box on the "Add-Ins" tab of the "Scripts and Add-Ins" dialog.

Unchecking "Run on Startup" causes the add-in not to be loaded in future sessions of Autodesk® Fusion®.

To uninstall this plug-in, exit the Autodesk product if you are currently running it, simply rerun the installer, and select the "Uninstall" button. 

Or, you can uninstall it from 'Control Panel/Programs and Features' (Windows 10/11), just as you would uninstall any other application from your system.

More information is available in the guide document.

If the plugin's icon isn't visible in Fusion, please run the add-in manually and check the Run on Startup option for the plugin on plugin's window:

Design workspace -> Utilities tab -> ADD-INS icon -> Add-Ins tab.

The second option for opening this window is pressing SHIFT + S.