Ok, I’ve just tested all machines and the post-processor and all is ok.
I believe you are saving the files individually using the browser and that does not work that good.
Please “Download zip” by selecting the green Code button as seen on the image below:
Then extract the folder Fusion 360 from the zip file and import from there.
I believe this is the problem.
As an alternative, to download just the files you need, please open each of them, select raw, and from the page that opens right-click and select save as as on the images below.
Try it out and let us know if it worked…