Hi @fgiuliani,
Very welcome. All hostname inputs during the install much be such that resolved from within the Kaltura server and the service URL must also be resolved from where ever you intend to open a browser to use Admin Console and KMC.
If 'kaltura-server' is not resolvable by the server on which Kaltura is installed then naturally it will fail to connect to it:)
For you other issue, go ahead and research it and if you can't understand the cause go ahead and open a new thread specifying exactly what you input, what the end result is and any other info that may help.