Not sure exactly what this dream is telling you personally,
but can reveal how it speaks to me.

I see the convention center as a place of "group thought" or mind.
This mind or thought is "conventional"

The diving board/platform/stage is set high above the crowd.
I look at these symbols and think, diving board- there's no water
so perhaps it represents an inward dive.
Platform could be a stance, like a belief or soapbox type of structure,
which upon expressing, would put you "on stage"

Something "free" is being offered- to all-yet to attain it is an individual process-
only room for one person at a time on the ladder.

Though you believe you are "first", there are already quite a few people
on the platform. Then you are informed the freebe is testing for AIDs.
Not what you had hoped.

I think you may be stumbling over the concept that "nothings free"
and you must "earn" everything. I stumble over this all the time,
which is why I see it in your dream.
What do you see?
Margie