Look at your 2019 tax return. There are two IRS FOrm 4562's in their for each property. One is titled "Amortization and Depreciation Report" and the other is "Alternative Minimum Tax Depreciation". They both print in landscape format. The first one will show you both the total amount of all depreciation taken for the entire time the property was a rental, and will also show your the amount of depreciation taken for the current year. Since this is your 2019 tax return I'm referring to, the "current depreciation" column will be showing your 2019 depreciation only.
If the 2020 program is asking you for the total amount of depreciation taken in prior years, then on your 2019 form 4562 you have to add together the amounts in the "prior years depreication" column, and the "current year depreciation" column, and enter that total in the 2020 program for the total amount of depreciation already taken in prior years.