Had this issue as well but would you happen to have purchased the Bundle for Racial Justice and Equality in 2020 or so? This full version of Lancer was included and I didn’t realize that I already own it myself so I was able to download it. IIRC everything from that bundle doesn’t automatically appear in your library as to not clutter it so the page here will show a purchase option.
Of course there’s also just the chance that the QR code is broken. But maybe you already own it.