Peak of Success Trophy

It's exactly 6th Special Volume of the Career, there's a right at the end of each of the six career stages. See Screenshots. To unlock the last band of your career above step 6, you must complete all 6 special volume.
 

Since new career levels are only achieved through the stars that are activated for podium places, other volumes have to be completed completely for the activation of the special volumes. You need stars and the number must be the number of volumes to complete. You have to bring all the stars to complete a tape and win all the races. I can recommend you to pick out volumes that make as few or no "Time Attack" and "Drag Races" as possible because these races are very difficult. The normal races are quite easy to win, there should be no problem. Although the "Time Attack" rules are pretty tough, as you often need to try until you can do it. There are often routes with many curves in the time races.

Note:
On Difficulty/Race Preset you can change. I can recommend you take that "Very Easy 20%" because it's very easy and you'll always win. You will find the "Race Option" in the game and select the race preset on "Learner". See Screenshots: