Have you tried logging out of the ibotta app or reinstalling, then attempting to link?
If this doesn't work, maybe wait until Monday to try again. The smaller regional grocers systems are not as sophisticated as some of the larger national retailers. Some of the backend maintenance takes place over the weekends.
If you still have issues, then you might want to message IB support next week:
This has been mentioned previously. This link might provide more information for you.
I'm also having an issue linking my HEB account to Ibotta. I've tried the instructions provided here but when I view the Terms, I do not see an option to Accept. HEB does show up on the main page so it appears it is "linkable".