I had filed my 2018 taxes with credit karma and trying to access it through my files on the site

This site is for TurboTax users. 

https://ttlc.intuit.com/community/intuit-account/help/is-credit-karma-a-part-of-turbotax/00/2092900

https://support.creditkarma.com/s/

credit karma files through turbo tax and we are automatically redirected to turbo tax. So it is also for credit Karma users who did their taxes through them.

I found this.  You have to log in through Cash App

https://taxeshelp.cash.app/s/article/Cash-App-Taxes