Please help, conversion issue from MVI to MOV

Hi, my original HD file is 6.5 GB, however, when it is converted into Apple Pro Res 4:22 (MOV), the file size becomes 24 MB which cannot be uploaded before the file size was too small.

I did many conversions before and don't know what goes wrong this time. Please help. Thanks!

Without knowing what system, software etc and all the settings of the original and how you converted it's impossible to figure out what you are doing right. ProRes 4:2:2 HD will in all probability be larger than the original.