You will need to reach out to EDB about this, as we do not control the state of downloads that are not directly hosted on the PostgreSQL infrastructure. There is a note on the downloads pages that provides more info:
"Note! This installer is hosted by EDB and not on the PostgreSQL community servers. If you have issues with the website it's hosted on, please contact webmaster@enterprisedb.com."[1]
Apologies for this - it's been resolved now and the releases should be accessible (as of some time last night).
I won't bore you with the details, but essentially it was down to a change in the way the EDB website is deployed. The CIO has taken steps to ensure that is not a bottleneck in the future.