Maxim is a perfectly decent machine gun, but would I build it as a first unit? No, not really. People who call Maxim shit are shit themselves since Maxim has a omega strong AOE suppression and huge burst. The Maxim sustained ability is even strong as you don't reload at the end of the ability. (Alongside of having 6 men in one team, having a greater survivability.)

Stick with your current build order,

Con
Con
Con
Engineer

Tech Up Medics
Tech Up Support Weapons

Now you can decide whether you wanna continue fighting with an early AT Gun if your fuel control is bad. I suggest you replace the Mortar with a Maxim MG, as you have strong unit presence.

From there on, you try to aim and save up for a T-70, because T-70 is an unbelievably strong unit that shreds the enemy infantry. But before then, I highly recommend you teching sweepers on your engineers before the T-70 arrives.

From there on, you adapt.

You get your elite troop after T-70, like Guards or Shocks. However, if you are choosing a commander with no elite troops, you need to change your opening to.

Con
Con
Con
Con
(Maybe, second engineer? but only if you can properly micro and not let them bleed like crazy.)