Installing via Rig Manager
Download Rig Manager at https://www.kemper-amps.com/downloads and install
Open the folder containing the Profiles you purchased from Multitracks.com and drag them into the Rig Manager App. They will show up in the local files tab in the app.
Connect your Kemper Profiler via USB cable to your computer and drag all the new Profiles to your Kemper. This can be done by dragging from the Local Files tab to the My Profiler tab.
Enjoy your new amp Profiles!
Installing via USB Thumb Drive
Take the USB that's been formatted for firmware updates and plug it into your PC/MAC.
Open folder named Shared and copy all the Profiles you purchased from Multitracks.com to this folder
Plug the USB in. Kemper should see the USB pretty quickly.
Inside the Kemper OS, push the external storage button.
Select Import.
Enjoy your new amp Profiles!