What is a schedule 1, additional income and adjustments to income?

As you noted in your questions, schedule 1 is where additional income and adjustments to income will be reported.  The 1040 form has been changed this year.  There is no longer a 1040A form or 1040EZ form.  There is only a 1040 form and 6 schedules (if the tax return requires them).  All amounts reported on Schedules 1 to 6 will then flow into the 1040 form.

Schedule 1 is where additional income, such as capital gains, unemployment compensation, prize or award money, or gambling winnings is reported.  Adjustments to income reported on Schedule 1 are for items such as: student loan interest, self-employment taxes, educator expenses, and self-employed retirement plans or health insurance deductions.

Here is a link to the copy of the Schedule 1 form: IRS 2018 Schedule 1 Form  

So do this mean that TurboTax can't file for free anymore as there is no 1040A or 1040EZ forms to file?

So this literally  means that, because I paid student loan interest, I have to pay more to file my taxes. Awesome.

@edingerk hate to say it, but I went to H&R Block, they filed it for free even though I had my Student Loan Interest on it.

Use H&R Block online. They're actually free, free free free.

wow turbo tax is losing my service on thisone

Major tax reform and major changes in the tax forms have also resulted in changes to the tax software.

WHY DO I HAVE TO PAY?  I WANT THE FREE EDITION

The information that you can enter in Free Edition is pretty limited now.  Thanks to the new tax laws, there are no more simple Form 1040EZ or 1040A's.  Everything goes on a little “postcard-size” Form 1040 that has six extra "schedules" with it, and if you need any of those schedules, you are not able to use the Free Edition.  

https://www.irs.gov/forms-pubs/about-form-1040 

If you qualify to use it, there is another free version of the software:

Try Free File: 

You qualify if your income was $34,000 or less, or $66,000 or less if active duty military, or if you qualify for Earned Income Credit

https://ttlc.intuit.com/questions/1900583-what-is-turbotax-free-file-program

• https://ttlc.intuit.com/questions/2026912-how-do-i-switch-to-turbotax-free-file-program

Note:  If you do not qualify to use Free File then you will have to upgrade to Deluxe or higher in the paid versions of the software.   

 Online Deluxe $39.99  State software $39.99 

 If you choose “refund processing” to have fees deducted from federal refund, add another $39.99  ($44.99 in CA)

REMOVE REFUND PROCESSING FEE

https://ttlc.intuit.com/questions/1900517-how-do-i-remove-refund-processing-fees-in-turbotax-online-and-change-my-payment-method

Or did you add a feature that you want to remove?

https://ttlc.intuit.com/questions/1899480-why-am-i-being-charged-for-turbotax-free-edition

What I don't understand is that I did not pay any student interest loans so why am I being asked to fill this form?

 

I looked at the form and none of the questions are relevant to me. Why do I have to pay more money to fill this form that I don't need?

So, under which category do i file Schedule 1 ?

It depends. If you have a situation that requires Schedule 1 to be filed, you'd report that situation in the appropriate section of TurboTax. Schedule 1 is created by what you enter into  your tax return. It's not a form that you receive and enter into TurboTax.