Turbo Tax is saying I made an excess contribution of $500 to my Roth IRA in 2018 but I didn't, contribution was $6500, I am 65 yrs old. What should I do?

Age is not the ONLY restriction ... did you also have enough income  or too much  income ?   Review the IRA contribution worksheet to see why you were limited ....

To view your entire return using the online editions (including the state) before you file, you will need to pay for your online account.

To pay the TurboTax online account fees by credit card, without completing the 2018 return at this time, click on Tax Tools >>> Tools  and then Print Center.  Then click on Print, save or preview this year's return.  On the next page, to pay by credit card, click Continue.  On the next screen it will ask if you want Audit Defense, if you do not want this option just click on the Continue button.  The next screen will ask for all your credit card information so you can pay for the account.

To make a Roth IRA contribution, you must have sufficient earned income.  Did you have at least $6500 in EARNED income in 2018?  Earned income is generally box 1 of your W2s  plus the net profits as shown on you Schedule Cs.