The A:M Films site has been fairly mothballed for some time now so it isn't too surprising the site is further broken.
Perhaps as a community we can look into what other options are available although those might be more unofficial.
In the meantime...
There are some other locations (primarily youtube) where product created with Animation:Master can be found although submitting new work has historically always been something of a bottleneck.
I believe Martin Hash himself may have uploaded the collection at Hash CG History: