Addictive drums is a multitrack vst pluggin and it won't install, HELP!!!

You should be able to run it as a standalone program, but as emmrecs says, you won't ever be able to control it from Audition - there's no mechanism for this at all. It's a little confusing though. I've lifted this direct from their website:

Formats

VST, AU, AAX (32/64 bit)

Standalone Application

Hosts

While XLN Audio actively tests on the host applications listed below, this product should run on any host supporting VST, AU, or AAX plugins. 

Cubase 7, 8, 9

Live 8 & 9

Logic Pro 9 & X

Pro Tools 10, 11, 12

Reaper 4 & 5

Reason 9.5 (In Addictive Drums 2, the Bus channel cannot be sent to a separate out track.)

Sonar X2, X3 and Artist/Pro/Platinum

So I can understand the confusion; it doesn't mention VSTi at all, but I strongly suspect that to use in conjunction with any other software, that's what the interface will be. The difference between Audition and all of the other software listed is that these are music creation programs, and Audition is, at heart, editing software. None of those programs (including PT) can hold a candle to Audition for that.