I'm not sure if this is an application problem or just something setup incorrectly at the Affinity Store, but the KolorMarc Studio Markers pack has 4 downloadable items: a brush set, swatches, and 2 .afphoto files.
The Affinity applications' Account Dialog in V2 (My Account in V1) doesn't show the 2 .afphoto files. They should be shown, with a link to take you to the Store to download them since they can't be installed automatically. As they're not listed, a user installing via Account might not realize they're missing 2 parts of the pack they purchased.
By the way, at the Store, when you click on Download to get one of those .afphoto files, you're presented with a dialog suggesting that you should install them via Account within the applications. While that's appropriate for the brushes and swatches, it's not appropriate for the .afphoto files as they can't be installed that way. For non-installable items, the dialog in the Store should simply perform the download.