Help! Premiere pro exports 4kb unplayable file

I have a video file that is filmed in 4k, original full export is 75GB and is 2 hours and 4 min.  I am trying to do an export at the highest quality settings that will be under 31GB to fit on a reformatted usb drive.  I have exported mulitple ways and 3 of them have exported as a 24kb or less unplayable file. I export to an unlimited dropbox, so storage isnt an issue. What am I doing wrong? I have been trying to research, but there is obviously something I don't understand correctly. I appreciate any help. I have been working on this project way too long. I have also tried exporting out of both premier pro and media encoder with no difference. (I have changed the bit rate several times, but maybe its still just too high? I am just trying to squeeze as much quality as possible into it. Thank you!