I managed to install
wget -nv http://public-repo-1.hortonworks.com/ambari/centos7/2.x/updates/184.108.40.206/ambari.repo -O /etc/yum.repos.d/ambari.repo
This allows Ambari 2.7 to be installed and it comes with HDP 3.0
It looks you are trying to install HDP 3.0, the best and working solution is to use the public yum repository but if you intend to use the internal repos then make sure your gateway/edgenode where you want to download the bits/binaries can access internet and the ports are open! I also noticed the HDP 3.0 is hosted in AWS
# wget -nv http://public-repo-1.hortonworks.com/ambari/centos7/2.x/updates/220.127.116.11/ambari.repo -O /etc/yum.repos.d/ambari.repo # wget -nv http://public-repo-1.hortonworks.com/HDP-GPL/centos7/3.x/updates/18.104.22.168/hdp.gpl.repo -O /etc/yum.repos.d/gpl.repo # wget -nv http://public-repo-1.hortonworks.com/HDP/centos7/3.x/updates/22.214.171.124/hdp.repo -O /etc/yum.repos.d/hdp.repo
Else the above will set up your setup your public repos. I just completed an install last night.