For a beginner at a track day, the minimum is a helmet (Snell 2010 or 2015), and a track inspection. Look for the forms from the organizer.
I do recommend a brake flush with high temp brake fluid. This reduces chance of brake fade. The M2C has great brakes but being hard on them all day long can boil stock fluids. The shop doing the inspection should be able to do it. Find an independent BMW repair shop in your area. That also eliminates concerns with the dealer knowing you track the car.
Most of the other items mentioned are recommended add-ons if you continue to track the car several times a year. Or consumables like tires and brake pads.
PS: Take a chair, sun tan lotion (you'll be sitting around outside a lot), water, snacks, basic tools including torque wrench and sockets to check lug nuts, tire pressure gauge, and an air pump. Or borrow stuff from a friend you know at the track
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2020 X3M non-comp, Alpine White over black : Exec Pkg, ventilated M Sport seats, 20"s
2020 M2 Comp, Sunset Orange/Blk: Orange stitching, DCT, exec pkg, bicolor rims
Gone '18 M550i, '16 X4 M40i, '15 M5, '13 X3 35i, '12 335is, '11 X5 50i, '09 Z4 35i, '08 550i, 06 X3, 06 650i, '02 M5, '99 540i