How can i enable a button with an other button ?

Your naming of var and func is very cofusing, as you give the same name to button and IBAction.

You call button1 (btnPasswortOk), but bthere is no button1 func defined

You should simply:

declare IBOutlet for each button

    @IBOutlet weak private var button1         : NSButton!
    @IBOutlet weak private var button2         : NSButton!

Then in IBAction, set the button as you want (here set button 2)

    @IBAction private func btnPasswortOk1(_ sender: NSButton) {
          button2.isEnabled = true
          button2.isHidden = false

It works, thank you very much 😉