After so many updates I lost track. Are Ancient Arkadian Vaults implemented or we are waiting for some VU?
They are in various locations in the underground. You need a treasure map, and go talk to the dude at Moonshine bar in Celeste Harbor... he will tell you more. This thread shows the Underground Map and the vault door locations.
If you were physically present on Arkadia when they were giving out various maps, then you have one in inventory. Otherwise, you can find the treasure maps on auction. I got 3 of the #3 maps for I think 41 ped or something like that (didn't realize I was buying 3 LOL). After you speak to the guy at the Moonshine bar, he will direct you to another NPC. That NPC will tell you what ingredients you need to bring him, along with the map, in order to get the "key". I can't recall what it was for the #3, but I have more, so I can go back and check.
Some time ago i receive 2 maps number 1 and 1 number 3. I take 1 map with number 1 and go to moonshine bar and see other npc later for "decode" map and receive the key tool. I do instance and try repeat with my second map. This is not working. Moonshine guy say a name for talk, but npc name at fuel depot is not same, and they not answer when i do click at him. Perhaps i do something wrong with my map 1. If i have 2 units but i split and use 1 i cannot use the second? Perhaps i must use both at 1 time?
Is it this Confusion in Map mission you are talking about? If not or even if it is add some info there or make a new Bug Report thread so it can be fixed asap please.
The name the guy at Moonshine bar say is not the same than the NPC you must visit. This is same thing in map 1 and map 3.
The maps also drop in loot, I received one during the last Oratan event, but I was not sure what typr of Oratan dropped it. A week or so later I was out hunting Oratan Miners with a friend and we both received a map each during the hunt, so I know that at least they are lootable from these mob. Regarding the actual instance, they are shorter than the Aakas instance and the levels are very different. Map 1 is very easy even for new players. For the Map 3 both of us were in plated Viceroy Armour and using Amped Piron PBR 27 and PLP 32 and we had to heal quite a bit to complete the instance.