The answer is "no."
If you are just getting into track events or autocross, you do not need to have R-compound tires. R-compound tires are very good and will help lap times improve as skill level increases, but I would suggest any of the top tires from the Extreme Performance Summer tire category or the Max Performance Summer tire category as a good option.
For example, I had the opportunity to get some track time on Michelin Pilot Sport PS2 tires (Max Performance Summer) on a Carrera S at the Porsche Sport Driving School at Barber Motorspors Park in Birmingham, Alabama. Both an amazing facility and an amazing car.
The Michelin Pilot Sport PS2 N-spec tires worked very well for me over the course of two days. The temperature both days was up in the upper 90s and track temperature was likely a lot higher. They had a high level of grip even as the track became a little more "greasy" as the day went on, the temperatures went up and the rubber was laid down. We definitely put the cars and tires through their paces as the Porsche driving instructors increased our speeds (which was pretty cool). The Michelin Pilot Sport PS2 is a tire that is very capable on the track and on the street, and it exceeded my expectations. Once you start to add bigger brakes and more power then yes, definitely switch to an R-compound track tire, but until then my pick is the Pilot Sport PS2.
Thinking about going to the Porsche Sport Driving School? It's an exceptional place to learn how to drive really fast with great cars.