FMNY

I got the United Club credit card about a week ago and tried it out for the first time today with mixed results. At Heathrow I was able to go in the Lufthansa Senator lounge, but at Frankfurt I was denied entry at the Lufthansa Business and Senator lounges. They even showed me a page that showed the United Club credit card with a big red X through it meaning not accepted for entry. The attendants said I had to show a physical or mobile United Club card, not a credit card. I never received a Club Card in the mail, only the credit card. I can't find a club card anywhere in the United App when I log into my account. The only thing I can find is under subscriptions it says I have a club membership. I showed that to the attendant, but he just repeated that he needed to see a physical club card or a picture of the club card in my app.

I believe I am supposed to have access to those lounges with my club membership through the club credit card. My boarding pass didn't work for access at Frankfurt or Heathlow, but at Heathrow they scanned my club credit card and that worked. At Frankfurt he scanned that and it did not grant me access. I will be passing through Frankfurt again in a few days. Did I do something wrong? Is there anything different I can do next time to get Lufthansa lounge access?

Thanks.