Sheesh! 582GB?!! Thats more than a couple of my hard drives. So yeah if its at 6K quality, that is why it consumes that much storage. Not sure how long you recorded these footages but I would assume its several hours long right? My advice in this situation is maybe try using OBS to screencap the main video itself. If you wish to take only certain portions of it, record that portion on OBS and save that portion on your computer so you can use it for editing. Be aware the quality may lower from 6K to whatever is the best quality format for OBS.
For OBS format settings: Go to Settings -> Output and then check the recording box and set it to what you need.
And you can go to settings -> Video to set the resolution of the video you wish to record.
That would be my advice because to be honest, converting and compressing that video to make it smaller in size may still take a very long time. And the OBS method takes a lot less time depending on how much video footage you wish to record. Hope it helps! 🙂