Some people have instead set Photos app on a Mac to download original photos from the iCloud library and then moved the files directly into the server. I have not personally tried this method though.
wait that is just crazy!!! Dang my dad is going to flip out when I tell him about this. He's got like 1.5 TB of photos in iCloud and has been searching for a way to get them off. And we're so close to our family storage limit that he gets mad at me when I text him pictures hahaha
I had to request again with 2G and I was able to download files finally. But only one by one. And after download 3~5 files, I had to login again as their login expires so frequently.
I had to do that for days and the download got expired. Oh my god. I had to request it again. And you know what? Their file list wasn't deterministic. I had to download from the beginning. lol
I finally made it and I swear I will never use any cloud service from apple.