I guess you tried something like this:
I haven’t tried to install it unattended, but the license prompt in there is very intentional. We don’t want anyone installing it assuming anything about the license it comes with.
If there’s a way we can keep that interruption for most users but make it easier for you I’m sure that would be of interest. I think RTI themselves made this deb, but @dirk-thomas knows more about it than me.