Low Poly Buildings nonfunctional?

I’ve installed Low Poly Buildings, and it looks as though I have uncompleted milestones in Tier 0, but the only milestones visible in Tier 0 are the vanilla ones.

Is this mod usable? How are the in-game low poly buildings unlocked/built?

Did you scroll to the right on the milestone list?

If so it may be a small bug from another milestone elsewhere on the tiers. I had that happen with a mod for a while; until I researched a certain milestone in I think it was Tier 2, Tier 0 wouldn’t register as being completed. I have no idea what actually causes it.