saying not enough space to transcode to proxy

have 779GB left

all the footage is 98.25GB

2 cameras are at .mfx and the 3rd at .mts

audio in mp3

all footage at 1080P (1980x1080)

any help would be appreciated

Thank you

Leaving aside that you should never work with .mts or MP-3 files, how is the media drive formatted and what are the read/write permissions.

how do i find that on a macbook pro?

Select the drive in the Finder and press Cmd-I.

Mac OS Extended (Journaled)

Are you able to transcode single files?
It happened to me in several instances that transcoding a whole (big) library in chunks worked while chosing all files at once failed with the same error.
Though in my case the spare harddsik space was much less.

So you could try to transcode a third of the footage at once.