How many databases for multiple instance?

What is best practice for setting up multiple instances environment regarding database? Is the idea to install and setup 1 database and then use it when setting up all instances?
I suppose that it is so because I want to reuse the music files and folders across multiple instances, correct?

Well that highly depends on how you want to use it.

If you want to use all instances fully isolated and not share any content, than you would setup multiple databases or multiple database users with it’s own set of tables on the same database server. PostgreSQL recommended.

If you want to share the same conten you most probably also want a single database but multiple station within this database.

You can do both. Even at the same time, use a few instances that share the same database and content and some, that are isolated.

Thank you for your reply. This gives me useful input in order to continue in right direction.