It sounds like you’re not using a version of Excel installed via a Microsoft 365 subscription.
The Foundation Template requires that you use a Microsoft 365 version of Excel. If you do have a version installed via a M365 account please make sure that you have installed all available updates for Windows and Office. If you don’t have an M365 subscription and prefer not to get one you can use Tiller with Excel Online and the Foundation Template will work in the browser based Excel Online version.