This is found inside the festival playlist (you must start in summer and progress all the way through to spring, seasons change every Thursday) you need to complete the 3 x PR Stunts for every season.
The Festival playlist can be found on the left on the home page next to the world map. It is also shown when you load up the game.
The events are 1 x weekly challenge, 7 x daily challenges (each challenge is active for 3 days before changing), The Trial, Seasonal playground games, 3 x Seasonal PR stunts, 3 x Season events/races (Drivatars must be Highly skilled or higher to get three stars) , 1 x monthly Rivals and 1 x online adventure. Monthly Rivals and online adventure only need completing once in any season to count.
If you have already got all three stars on the base game to get
You will be familiar with these jumps, speed traps etc. the only problem is that the seasonal targets are harder, so if you just scraped by to get the three stars you will need to do better to get these. With the correct car, tune and setup you should be ok, if you are struggling look on YouTube and you may find a better setup or start point to attack the challenge. I cannot really give tips on each PR stunt as they change every season and every year.
Repeat this on the other 3 seasons to obtain the achievement. I would advise to complete all the challenges on all 4 weeks which will get you these
The Encore? achievement in Forza Horizon 4 worth 336 pointsComplete all activities in a single Festival Playlist Series.