Why did I have to pay $90 to file when I didn't have to file for a state return?

You appear to be using Live Deluxe.   At least that is what is displayed underneath your question above.   That product is $90 for a Federal return and $50 for a state return (if applicable.)

Live Deluxe is the upgraded version of Deluxe that has on-demand live tax help from a CPA/EA during return preparation and a final review of your return prior to filing.

FAQ:  What is TurboTax Live?

https://ttlc.intuit.com/community/choosing-a-product/help/what-is-turbotax-live/01/27191

Have you already paid and filed?  If not, it can be removed prior to paying:

FAQ:  How do I remove Live?

https://ttlc.intuit.com/community/downgrading/help/how-do-i-remove-turbotax-live/01/27312

If you already paid and didn't realize you were in Live TurboTax, you can talk to Customer Support.  I don't know what they will do/say.   They may say that continuing on to pay and file indicated acceptance of the terms, but if you wound up in it by accident and didn't use any Live features, it can't hurt to ask.

Hours are 5AM-9PM Pacific (8AM-12 Midnight Eastern), 7 days/week

FAQ: What is the TurboTax phone number?
https://ttlc.intuit.com/community/using-turbotax/help/what-is-the-turbotax-phone-number/00/25632