Usage of なければ　なりません：

なければ なりません - (I) must....

This expression means something has to be done regardless of the will of the actor.

Important Note: This is not a negative expression.

まいにち べんきょう しなければ なりません。

I must study everyday.

Particle まで に：

まで に Indicates the point in time when an act or an action should be done by the latest. That is, the point in time indicated by まで に is the time limit and the act or action is to be done before that time.

よる １２じ まで に センター へ かえらなければ なりません。

（We) must go back to the Centre by 12 0'clock at night.

*Make sure you do not confuse まで に With the particle まで Or particle に

まで Indicates the point in time when the continuously performed act or action ends.

ひる １２じ まで にほんご を べんきょう します。

（We) study Japanese until 12 o'clock noon.

に Indicates a point in time when a momentary action takes place.

あさ ６じ に おきます。

I get up at 6 o'clock in the morning.