"force" login to access site – not "membership"

Hello Everyone,

Is there a simple way to make it so that a WP site can only be accessed by a person “logging in”?

I do not want a unique login for each individual user. I am going to have a few “users” that people will use; for example:

u/p: apple/core
u/p: orange/juice

etc.

And there will be different content seen based on which username/password they logged in with.

Again, I don’t want a unique user created for each person that is coming to the site.

TIA,
Greg