You should probably check with the person who invited you to collaborate—they may have removed the link or folder access by mistake.

Still having the same issue.   They sent me another invite and I logged in following their invite. Still I cannot see their shared files or folder.

The first second I log in, I see like a shadow of folders then they disappear then the same msg. "Oops! We can't seem to find the page you're looking for".

Hi Mimi, I'm getting the same thing.   Yup, even see a split second flash of there being a list of folders/files, then it returns to the 'Oops page' again.   Did you ever get this resolved?