I see the default download from Studio, for decorous template is already set to una 13 Alpha version, but since you are using the stable una version 12.1, it will give you the error "The package isn't compatible with your UNA version".

What you can do is to manually download the correct template version for UNA 12.1 here from the market: https://unacms.com/page/view-product?id=81 unzip it, upload it to modules > boonex and then go to your Studio > Apps Market >Downloaded tab, and Install it from there. That is one way i know...