How could we get into stage 2 in the lost grove?

but filling the requirements to complete stage 1. The NPCs and the zone progression task tracker tell you what you need to do.

The list is (so far as Amarok's LG walkthrough lists it, which I assume has roughly the right numbers)
Ancient Timber x ~ 10
Enchanted Cloth x ~ 13 or 14
Tempered Steel x ~ 6 or 7
Spritely Branch x ~ 200
Reclaimed Supplies x ~ 88

Which are obtained as enemy+elite/boss drops and sometimes from chests, and given to the gold-armoured npc