Good morning
The program may rename the files in this way:
if they have exif data
preference 1 - take the date "date taken"
if they don't have exif data
preference 2 - take the "creation date"
if they don't have "creation date"
preference 2 - take the "modification date"
In this way the files that do not have Exif, would not remain unnamed
Thank you so much