I know some were interpreting it as 5 squads, although it says infantry squads.
That I would not be willing to brook. Infantry Squads are a unit entry, Platoon Command Squads are an entry, and Heavy Weapon Teams are an entry (all making up an Infantry Platoon of course). All have different attributes, upgrades, and profiles. Five Infantry squads is five infantry squads, not a PCS two Infantry Squads and two Heavy Weapons Teams. From the Codex, concerning the composition of one Infantry Platoon:
Composition: 1 Platoon Command Squad, 2-5 Infantry Squads, 0-5 Heavy
Weapons Squads, 0-3 Special Weapons Squads and 0-1 Conscripts Squad.
At this juncture I would like to point out GW has edited out the 'all you need for this Formation' comment in the original blurb for this online bundle, I just mean to point out that pictures aren't always the way it works.
The Mont'ka stuff is meant to relive a larger battle than what a Decurion-esque 'super Formation', which is more commonly found in a Codex and not a Campaign book, would and so the unit compositions are through the roof. When the AM 'dex gets a proper 7th edition release with all the bells and whistles the other more current books have we'll see smaller more usable Formations for the average collector I imagine.