I'm on my phone and can't open the file but joining and spectating in general is not working for me at all. Spyder brought it to my attention a week or so ago (it was news to me. It has always worked for me in the past).

But now nothing happens. I get the waiting message but just end up where I was when requesting the teleport.

Here's a direct quote with a pretty reasonable explanation:

In A3, when you spawn a a large amount of units or vehicles in a short period of time it can cause the game to stutter. In order to solve this issue ALiVE introduced a slow-spawn method that slows down the spawning of profiles in order to eliminate stuttering. Unfortunately, the slow spawn method sometimes breaks the join group feature if the group doesn't spawn fast enough. There are two ways to fix this on our end, one is very hacky and not optimal and the other introduces a potential issue where ALiVE-induced loading screens might never end if coded improperly. It also seems to not work properly when you select a vehicle group to join, I have not been able to solve this part..
 
So my apologies with that feature being kinda broken  :)