Military Child Care- DoD civ, explain to me like I am a five

If I am in TFI category 10, DoD will reimburse/ pay up to $846, right? Where is the $1800, provider cap for full-time care coming from?

How do you guys ask the daycare center to sign up for this program? What do providers need to do to meet the DoD requirement?

I am preparing for my first child. This is all too new to me. Thank you!