Deals are targeted. A deal is visible to you when you meet its campaign's criteria: things like platform, follower range, views, or a minimum Artec Score: or when the brand invited you directly.
If someone sent you a link to a deal you're not eligible for, you'll see a "not available" screen instead of the details. That's expected: it means this particular deal's criteria don't match your profile right now.
What helps: keep your social accounts connected and synced (your stats are what eligibility is checked against), complete your profile, and grow your Artec Score: brands often set a minimum.