Fortnite PC with others talking is also possible without push to talk?

And I would like to know how to talk without talking to others at fortnite without having to press a button.

For this you have to turn off exactly that in the settings. There's the setting "Push-to-talk", which you then have to turn off. However, you must also look in the settings, whether the "voice chat" have turned on. If you did that, then you should actually be able to hear and speak.

Have fun playing.