Your unused RRSP contribution amount from previous years will be on your RRSP Deduction Limit Statement, found on your latest notice of assessment. If you used CRA’s Auto-Fill My Return, TurboTax automatically downloads the contribution amount into your tax return for you.
Here's a great FAQ for your reference:
https://turbotax.community.intuit.ca/community/pension-retirement/help/how-do-i-claim-unused-rrsp-co...
