I ignored the TRC on my two previous TATL flights because I departed on non UA metal.
Now I have a flight coming up on UA metal.
Does uploading your CDC card pic mean they won't ask to see it at the airport?
Otherwise, on my previous flights, I had to show at check in.
How does TRC change or not change that process?
You will still need to show it at airport. The TRC just let you check in on App/United.com at T-24 h and have an electronic boarding pass. Document check is still needed at gate or United Club if you can access to UC.