If you’re trying to get the sum for each record individually, that’s

{Count Column 1} + {Count Column 2}

or

SUM({Count Column 1}, {Count Column 2})

If you want the total of all values across all records from both Count Columns, you need to either run a script or link all the records to one common record and use Rollups to do the summing.

Formulas can’t “see” values not attached to the current record, Rollups can’t see values not attached to the current record or linked records.

I used your second formula and it was exactly what I needed - thank you!!