Trying to download huge file from icloud

I have a huge file over 200GB in my icloud. (It is a final cut library)

I'm trying for months to download it to my mac but it never works.

I tried through wireless and cable. Both doesn't work. Sometimes it continues to download up to 50GB or so and suddenly the downloading process stops. Sometimes it says it's downloaded successfully but it's only 5GB or so and when I try to expand it, it says it is inappropriate file format.

Is there any way I could download this file? It's a very important file. I would've never let it uploaded to icloud if I had known it would be so hard to download it back.