I never paid alternative minimum tax in a prior year but Turbo Tax auto checks the box for me. I don't have the forms it's asking for so I'm stuck. What do I do?

Yes, if you filed taxes with Turto tax last year, the AMT dialog box will come up automatically.  It's an alternative tax that calculates along with your regular tax. Below are simple instructions to enter or clear AMT.

1. Login to Turbo Tax
2. Under Other Situations tab, click Alternative Minimum Tax, then click start.
3. Next screen, "Let's See if  you need to pay AMT this year"
4. Read the screen, you must answer yes or no.  
5. Select yes, if you have any common deduction in 2020 such as standard deduction, state and local taxes paid, and excess ISO.
6. On the screen " Do you have any of these uncommon situations" will deternine you need to pay alternative minimum tax. Below is a screenshot of the screen.

Indeed, so I know AMT doesn't apply to me, so I selected the "does not apply" option. However, when I get to the state-specific section, it forces me to check the AMT bubble - even if I manually de-select it. Then, it won't let me continue without information from forms that I don't have.

Additionally, now I can't go back to the section you screenshot because any attempt to go back to a previous section gives me an "undefined" error and logs me out. It's totally possible I checked the wrong box so I'll keep trying to go back, but I'd appreciate any additional support.

I am having the same problem with the Minnesota State return.

I was able to proceed by just leaving any of the amount entry fields blank and clicking to continue.  It seemed to work fine from there.

I'm having the same issue with the MN state return

Let's make sure the questions were answered accurately.  Do this:

If you filed taxes with Turto tax last year, the AMT dialog box will come up automatically.  It's an alternative tax that calculates along with your regular tax. Below are simple instructions to enter or clear AMT.

1. Login to Turbo Tax
2. Under Other Situations tab, click Alternative Minimum Tax, then click start.
3. Next screen, "Let's See if  you need to pay AMT this year"
4. Read the screen, you must answer yes or no.  
5. Select yes, if you have any common deduction in 2020 such as standard deduction, state and local taxes paid, and excess ISO.
6. On the screen " Do you have any of these uncommon situations" will deterrnine you need to pay alternative minimum tax. Below is a screenshot of the screen.

Ok, I went ahead and double checked.

I select "yes" because I took the standard deduction last year and that's on the list.

Then I select "None of these apply" for the next options because they don't.

It's confirms this and tells me my AMT total is 0 and double checks my federal section. All looks well, no special situations to deal with.

Then I get to the MN state section and it STILL forces me to select the AMT button and I can't de-select it. Then it continues asking me for further AMT information that I don't have. 

Also, I just noticed that this solution is just a copy & paste of the initial response to my OP. I'm just going to do as another user has suggested and input a bunch of zeroes to force it through.

I'm still not able to proceed to the next page after the General Business credit page. I have no credits and placed a 0 in all boxes and I still can't go

You can try deleting Form 6251  Alternative Minumum Tax - Individuals. That may resolve your issue.