Rename and move old photos

Hello guys and thank you for such a great program. I`m using a synology nas with photos app that is managing the newer photos taken with phone using this format IMG_20210914_151014.jpg
With Advanced Renamer I managed to do this using IMG_<Year Modified><Month Modified><Day Modified>_<Hour Modified><Min Modified><Sec Modified> but is not the correct date like in exif creation date. If I`m using Creation is also incorrect.
How can I use exif info but to have the same output like above? Because using IMG_<ExifTool:DateTimeOriginal> I`m not getting the desired name.
Second question is for format type. What should I use to have IMG_ for image types and MOV_ for movies (.mp4 .mov etc) ?

A little edit: after using “Date original” on program data and IMG_<Img Year><Img Month><Img Day>_<Img Hour><Img Min><Img Sec> is getting some correct results but on many images I don`t have any dates, and using exif tool for those images for example the FileModifyDate is 2016:12:26 13:45:01+02:00 and FileCreateDate is 2021:09:28 13:42:37+03:00. There is no original date or Taken date on them.
My third question is how can I use something like if Date original exists, use method if not use FileModifyDate ?