If the property was not "available for rent" (meaning it was move in ready) on or before Dec 31 of the tax year, then you have nothing concerning this property to report on SCH E on your 2020 tax return. The only things you can deduct on your 2020 tax return are SCH A itemized deductions. Those two items would be property taxes and mortgage interest. That's it.
Most likely, you did not receive a 1098-Mortgage Interest Statement for 2020, because my bet is, your first mortgage payment was not due until "AFTER" Dec 31, 2020. So your SCH A deductions of mortgage interest and any property taxes you paid at the closing, will be on your closing statement only.
I would suggest you bookmark this thread for next year, so you can refer to it when asking for help completing your first SCH E on this property for your 2021 tax return; which you will not deal with until next year.
