Don’t use apt-get. It can’t help you to install Editor.
But of course, use apt-get, or what other means you prefer, to install Java first.
The installation file you download from Allen & Heath is an automated installer, equivalent to a Windows .exe.
To run the installer, you likely will have to change the file’s permissions.
Right click on the file, and under properties tick the “allow execute file as program” box.
Then you can (I’m pretty sure) double-click the file to initiate the installation wizard. This will install Editor in a Windows-like way.
It can create a shortcut on the desktop to launch Editor as a finishing touch.
If this method doesn’t work, there are other more certain ways to make the installer work by typing commands in the terminal. I didn’t include them to avoid further confusion.
Good luck.
As an aside, I’m grateful that A&H unofficially supported Linux when most other manufacturers can’t be bothered whatsoever with Linux. So thank you, A&H.