You’ll have to export as a Merge file from FileMaker.
Then take a look at whatever date format is used for the dates in the .mer file.
Set Tap Forms to import that date format. Look at a bunch of the records to see wha the dates are. Sometimes it’s hard to tell if 1/2/2019 is Janary 2, 2019 or 1st of February, 2019. If you see something like 1/31/2019 then it’s easy to tell which the month and day is.