>>2001075You can download them right before/as you leave generally.
I started alltrails (using it) in Dec 2019 and found I was able to download a map layer deep within the Appalachian mountains in PA (tho PA as a state in my experience tends to have pretty decent cell reception compared to WV).
Even if you can't download the map layer you still will have the blue dot and red line, just no background map.
Also another tip would be to download multiple trails in advance in case a trail doesn't somehow work out (no parking, poor trail conditions, impossible to access).
I download 10-25 different trails for a multi-day trip, many short trails, so I can do little pieces of multiple trails in a day rather than necessarily committing to one long trail.
You can whinge and moan about phones and apps being evil or try it yourself. If you don't like it, that's fine, but at least try it.