Unfortunately, it's only available for Builder+ users. One of the admins has already made it clear it won't be made available for all users, due to fear of vandalism. (forum #156)
I will say that generally the bar for promotion on AIBooru is lower than on Donmai by some degree so you'd just have to wait and it'll likely come. Do what you can with tag edits or just upload a good amount of decent/high-quality images and you're golden.
Then again, I'm not an admin so I don't have final say but I hope this is somewhat helpful as an answer.