From my testing, you have 3 options.
1st Tracker Area alone. No reinforcements. Selection will have:
a- Sentry = 9 groups of 2
b- Patrol = 6 groups of 4
c- Avalanche = 5 groups of 12
2nd Tracker Area + Tracker Group Reinforcement Requester. In this case you need to select "Trackers", which will spawn 9 groups of 2, but each of them, when entering the combat mode will call 2 Fire Teams of 4 (the 2 teams will spawn nearby)
3rd Tracker Group Reinforcement Requester synched with group leader of Editor placed group. Same, the group when in combat will call in 2 Fire Teams. (you can also still use the Tracker Area set on "Trackers" too.)
NOTE. Reducing the size of the Area will change the numbers of groups (I don't think is directly connected, but the system clearly checks the "spawning distance from player", avoiding spawning large groups too close). Placing 2 Areas nearby will have the first activated slowly de-spawning groups, while the new one the player entered start spawning in. I love the system. It allows to have enemy patrolling around the Area I am playing.
WARNING. using Tracker Area (set on trackers)+ Group Reinforcement Requester for me got the enemy total number going up to 60/70 AI every time.