After upgrading your GMC vehicle with the io5/io6 module, you may notice the MyLink application suite is not updating. If you had MyLink before this upgrade, you will need to reinstall your previous HMI and de-register the module using your MyLink app on your phone. After re-installing the new HMI simply link your service using the MyLink app on your phone.
If you did not have MyLink before upgrading to the new module, you will simply need to subscribe to the service. However, if your vehicle is older than 2017 year model, you will not have the ability to subscribe to MyLink due to the vehicle's OnStar module lacking MyLink software compatibility.