Hope you are doing well.
We sincerely apologize for the delay.
Apache Ambari is not comaptible with Ubuntu.
Please download CentOS 6 (64 bit version) from the link given below.
http://archive.kernel.org/centos-vault/6.5/isos/x86_64/CentOS-6.5-x86_64-bin-DVD1.iso
Follow the given link to install Apache Amabari
Please let me know if you have any further issue regarding this.