The city has acquired a 24-acre hilltop on the west side, moving forward its ambitious plans to open the first career academy of its kind in Connecticut by 2024, and provide badly needed classrooms for a student enrollment that has outpaced projections. Danbury closed on the Apple Ridge Road property formerly used by Cartus Corp. on Tuesday afternoon and rezoned the light industrial campus into residential zoning on Tuesday night, clearing the way for the city to take the next step for the $164 million project. The state has agreed to reimburse Danbury for 80 percent of its classroom construction costs. The new career academy would overlook a west side that continues to lead Danbury’s economy with large-scale residential development and new business activity. To get the academy plans off the ground, the city needed to revert to the zoning that was in place 40 years ago when the biggest thing on the west side was the Danbury Fair.