The OC pays. NBN charges them $275 multiplied by the number of units. That’s all units – NBNCo won’t connect less.
The OC may choose to raise the money by a special levy. If so, the contributions are in proportion to unit entitlements. Provided the OC is better at arithmetic than it is at strata law, the average might be $275.
The motion will need to be expressed as a special resolution and will need at least 75% by value of votes cast.This is because it seeks to vary the common property.