You do not need to use the browser extension for the free thanksgiving at Walmart. Go to this scroll all the way down and put your email you use for Ibotta in. In about an hour it'll be on your app under free thanksgiving in Walmart.
Did you go into walmart on your app it's the 1st category says free thanksgiving, see for an update uninstall and reinstall the app? If that doesn't work it could be that they didn't give it to you not everyone gets the same rebates and bonuses