How to create folders in android 6.0 app drawer on an LG phone?
Well I think I found the answer to my own question. 

You can create folders if you are in default android 6.0 app drawer this way:

press and hold the right hardware button (the square one) while being in the app drawer screen, then select 'edit/uninstall apps' and drag an app onto another one. This creates a folder with these 2 apps inside it!