what am I supposed to do on astral stair?

[ya boi]

I played through it but could not find a way to get to any of the relics in the stage

[Matthew]

There are doors along side the walls. They are hard to see because they don't look like doors unless you look real closely. Just walk up to them and it will transport you to another portion of the map.

[Cahos Rahne Veloza]

The doors look like the Spade Card Suit in Poker, and yeah they're a bit too difficult to see as they blend with the brown paneling of the wall.