The easiest way to tell is to think of the slave switch as wired like an outlet, with the traveler back to the primary switch. IOW, all the slave needs is power (like an outlet would) and the traveler. It doesn't actually connect to the load at all, like the regular 3 way would.
So if you can figure out which wire goes to the load (looks like your wire2 upstairs), and which wire is your hot (wire1 white), bring the hot into the primary switch, then send the 'switched' side of the primary to the load.
At this point the primary should be controlling the load. If it is, you're wired correctly and you can just put the slave switch in the box and provide power to it, then connect the traveler to it and to the "slave" wire on the primary.
I would say you have it wired wrong and should redo it immediately.
These "group of" wires, is there another romex in the upstairs or is it just 2??
Looks like the original has power coming in (group of blacks), which is then sent to the DS's common using the wire1 white. Then the black and red are travelers back to the Up stairs box and wire2's black is on the common there sent to the load.
So disco everything. Run power (hot and return) to the primary upstairs. Then connect the wire2 black to the load of the primary.
This should now control the load. Does it?
Then just wire the slave as I described above.
Actually just looked at your diagram again, it is wired correctly but you should reverse the wire1 so that black is hot and white is return. That's what was throwing me off, seeing the black from wire1 going to the whites. Again, the primary does everything, then just send power to the slave so you can just connect the black from wire1 to the 'group of blacks' and the wire1 white to the 'group of whites. This willbring "normal" power to the slave.
Sorry about the confusion.
