Could you specify?

uh yes, the big vehicles like the skoff, the dropship, to get them as an actual useable thing you need to do the Vanguards Weapons quest, i can't find said quest.

The quest is called "Vanguard's vehicle", it's the one where you get to test the Avikan mech (Khral).
It's given by the avikan near the entry point (upper level, left to the teleporter) if I remember well, might be his second or third quest as well. After that the vehicles controllers are available at the vehicle shop at the lower level.

I have the same problem as OP (except he mispelled the quest name, it's not "Vanguards Weapons" but "The Vanguard's Vehicles".
I found in a wiki that Rokhan will give you that quest after completing "Stopping the Corruption" but Rokhan doesn't seem to give me any other quest after that.
Are there any other steps/quests I need to do to make him give me the other quest?
Maybe there are pre-requisites not related to the starfarer's refuge progression.

SOLVED (after a lot of testing):
To get the "The Vanguard's Vehicles" quest, aka the prerequisite to buy functioning avakin vehicles, you need first to complete the following steps:

-Complete "Test Drive" vanilla quest (not sure if really needed).
-Complete the vanilla tech quests until you complete "Jumping To The Right Conlcusion".
-If you have completed all the above mentioned vanilla steps, Rokhan (in avakin starfarer's refuge) will give you "The Vanguard's Vehicles" quest just after you complete "Stopping The Corruption".

I had a lot of confusion because the guides/wikis I read, claimed that you had to complete other starfarer's refuge quests, but the only one is "Stopping The Corruption", given from the same quest giver Rokhan.

-->I think that a lot of people like me just tested this on a fresh character, going straight to the avakin refuge, missing the few vanilla tech quests needed.<--