To activate the command you can:

• Click on the corresponding icon in the Add-in tab
  
• Type the command FCEASYATTACH

It remains for you to select all the desired files.

The installer that ran when you downloaded this plug-in from Autodesk App Store has already installed the plug-in. You may need to restart the Autodesk product to activate the plug-in. To uninstall this plug-in, click Control Panel > Programs > Programs and Features (Windows 7/8/8.1/10) or Control Panel > Add or Remove Programs (Windows XP), and uninstall as you would any other application from your system.