Hello!
This may be due to the fact that no photos are public. I haven’t looked into the issue much, but when going to the user page, I see that there are no public photos, so I think this is why you are seeing the 404 page. I could be wrong, but that’s my initial thinking.
Maybe you could make an image public and try clicking on that image from within the website.
Let us know what you find.
Thanks,
Josh