Note: I'm only gonna cover one of the possible objectives here, since you only need to clear one and there's no benefit from clearing the others. Since you can do the below objective in a pacifist manner, this the best one for most people to complete if they're just looking for a fast clear of the collab.

Objective: Find the secret node and capture it.

Echelon Limit: 2

Recommended Echelon(s): Dummy (x2)

While the objective is kinda vague, thankfully we know exactly which node is considered to be the right one for this. It's located off to the left, once we reveal that section of the map. We get a tiny portion of the map unlocked initially, so we need to unveil the rest of it. That's our first move. Ignore the marked node on the map and head to the left of your Command Center. Deploy a dummy echelon after. Don't worry about that enemy, it won't fight you.

On turn two, move to the left again, and this time it'll reveal the rest of the map. Go as far left as you can with the AP you have on hand. We'll be staked out here for a while to see if the pathway down to the bottom of the area will be clear. You may need to wait and figure out if the path is clear for you to move straight down or not. The patrolling enemies can be slightly random, but there should always be some point where you have room to sneak past them. 

Once you're able to sneak past them, head as far down as you can go. Now we can head to the bottom right of the area, where the secret node is. If you haven't figured it out, it's the node just jutting out of the rectangle shape we have in this area. Going over to it will reveal that there's a loot stash there that you can pick up. Grab it and end your turn there to capture the node, ending the map.

Video of me clearing this map