What are the criteria to achieve the different access levels

Simply put, there are none. Other than Exile (banned) and Avatar/Senator (SD employee or volunteer helper), ranks are based on entirely subjective judgements by Stardock based on how helpful you've been to the community. If you want to get a higher rank, all you can do is be a good and helpful member of the community, or contribute positively in other ways. If Stardock thinks you deserve it, they'll give you some goodness next time they hand out promotions

Thats how im a Veteran say lots of BS but most of it is actually informational if you can understand .

Ah, so you don't become a veteran by posting 60 katrillion times!