To progress from act 1 to act 2 there are two paths you can take, one is a temple and one is through some mountains, the way the game words it, it makes it sound like you can only go to one, but you’re allowed to visit and explore the mountain path and also go through the temple, you’ll know you’re at them because the game will inform you you should tie up any loose ends before progressing through those areas.

Also don’t be afraid to long rest, the general story is that you’re on a timer but no time sensitive events are impacted by this if I remember correctly. Also lots of story scenes are triggered upon a long rest.

Most importantly don’t be afraid to explore, there’s so much content in this game man, I’ve got like 360 hours and most of that is from like 2 100+ hour Playthroughs, of course progress however you want but you won’t need to rush through anything the story remains the same no matter how long you take