My daughters college expenses

You can claim the deduction if all of the following apply:

• You paid interest on a qualified student loan in the tax year 2019.
• You can take the deduction as a parent making payments on your dependent student’s loan.
• Your filing status isn't married filing separately.
• Your MAGI is less than $170,000 for married filing jointly, $85,000 for single and head of household filers.

A qualified student loan is a loan you took out solely to pay qualified higher-education expenses that were:

• For you, your spouse, or a person who was your dependent when you took out the loan.
• For education provided during an academic period for an eligible student.
• Paid or incurred within a reasonable period of time before or after you took out the loan

Please see this link for more details:  Can I claim my Student Loan?

What do you mean by "add the student loan".

In order to claim the student loan interest deduction, you must have actually paid the interest and you must be legally obligated to do so.  So, if you were neither the principal on the loan or a co-signer, you may not claim the deduction.

If you are trying to enter student loan payments of tuition, so that you can claim the tuition credit: Turbotax is no interested  in whether you paid tuition with loans or out of pocket.  You may not claim the tuition credit if your daughter is not your dependent. It is harder for a student 24+ to be a dependent.

There are two types of dependents, "Qualifying Children"(QC) and standard ("Qualifying Relative" in IRS parlance even though they don't have to actually be related). There is no income limit for a QC but there is an age limit, student status, a relationship test and residence test. Only a QC qualifies a taxpayer for the Earned Income Credit. Since your daughter is over 24, she can not be a QC.  

A person can still be a Qualifying relative dependent, if not a Qualifying Child, if he meets the 6 tests for claiming a dependent:

1. Closely Related OR live with the taxpayer ALL year   (not even one night at the non-custodial parent’s home).
2. His/her gross taxable income for the year must be less than $4200 ($4150 in 2018)
3. The taxpayer must have provided more than 1/2 his support

In either case:

4. He must be a US citizen or resident of the US, Canada or Mexico
5. He must not file a joint return with his spouse or be claiming a dependent of his own
6. He must not be the qualifying child of another taxpayer