Well, let me put it this way: installing Nextcloud the old fashioned way takes two command lines and is a fool-proof 5-minutes long process with no hitches whatsoever.
How in the world they promote this docker thing as being the easiest and more convenient way to get Nextcloud is beyond me. Sure it may be better at managing it once you have it, but they sure made the road to get there as elitist as they could.