I arrived in the step where i have to download the Ambari Repository (I'm using Ubuntu as OS)
and when i try this cmd:
I get this message:
gpgkeys: key B9733A7A07513CAD can't be retrieved
gpg: no valid OpendPGP data found?
By any chance are you running any HTTP proxy on your Ubuntu host? If yes, then you should also supply the proxy options something like following: