Most often, you have to access the software from the 3rd party affiliate link for promotional offers. Unless you are US military, then no special link is required. Which promotion program are you inquiring about?
How to get the partner discount
I used two different affiliate links to log in on two different computers. Still didn't work. Have the same problem every year. This is a scam, if it so difficult to claim the discount advertised. Each year, I have to call into Turbotax and have them manually apply the discount to my check-out process, because they can't get it to work, either. Enough Turbo Tax, just stop with the fake discounts.
No, no, no. Don't give people this canned response. It doesn't work. At least not on my computers.
Spit Balling:
Maybe a cookie blocker on your Computer?
....or Browser issue? The Brave browser has been known to block all kinds of things that feed into TTX, until folks tun off that browser's high security or firewall settings.
....or a high security setting on whatever browser you are using that doesn't hold/keep the cookie, or whatever background code is needed such that the discount is applied?