It says Digital Membership Card is available on the Costco app. https://www.costco.com/costco-app.html

I followed the procedure step by step, but I couldn’t get it to work. I don’t know how to verify my membership. I logged in, but it doesn’t verify my membership. I gave up after a little try. I shall try again in a month or two.

Let me know if you got it to work.