There is effectively no error in the link. In fact, it works for us if we are logged into the developer’s hub. If we are not logged in, it does not work and, therefore, there is a restriction to be publicly available. In your case you could have the necessary “permissions” to access.
We uploaded the addon 17 days ago and there is still no solution: neither the link is publicly available nor is it listed in addons.mozilla.org. It keep in the “Awaiting review” status.
We do not know if something is inconsistent and, therefore, we are requesting help to solve this problem.