Why is it saying I have to pay back all of our premium tax credit when we did not make over 80k?

you did not tell us your family size or modified adjusted gross income.  but here's an example: Husband and wife living in the continental Us (lower 48 states) with a modified adjusted gross income of over $68,000 would have to pay back all of the premium tax credits.  review form 8962 to see if the numbers on it make sense. we can't see your return.  

We are a family of 3, how much are we allowed to make Max?

The federal poverty level for a family of three is $21,720 in 2020. So, your premium tax credit would not be allowed if your income was over 400% of that, or $86,880. You can read about that here:

https://www.healthcare.gov/lower-costs/

You would have to look at form 8962 to see why the credit is being denied.