The Osprey is totally unreliable... that looks very much like an approximation of a British Army Infantry Platoon of 1940... which even the British weren't using until after their 1938 organisation.
As the battalion had a 'Machine Gun Company' at Jarama, I'm inclined to say that it followed the same organisation as the rest of the EPR... which currently I have yet to research myself.
*Edit* - From what I can tell at first glance, the EPR largely used the same 'Platoon' structure from March 1937 as it had pre-War. What differences there were came higher up the organisation. The infantry guns were removed from the battalions and the 'Machinery Section' became a proper Mortar Platoon of four tubes. The Machine Gun Company was formalised at two platoons of 4 weapons each, plus the usual infantry complement within those units.
The battalion strengths appear to have been successively increased by small amounts over time however, but whether this meant that the original 6 man squads were eventually increased to 7 and subsequently 8 man squads is hard to tell. I've read elsewhere that rifle companies received their own mortar and mg sections, which may account for the increases in manpower and possibly a reduction to 5 men in the usual rifle squad.
I'm not certain but I believe an anti-tank company was added at brigade level (i.e. 1 per four battalions) and the 3rd Brigade of each Division gained an 'armoured platoon', which if I am correct, means tanks in this context, as there was already a theoretical armoured car company attached to each brigade.