A crash course is an intensive training program, where you take driving lessons almost every day. In this way, you quickly build up skills and experience. A talented student, who starts from scratch, can be ready for the exam after a minimum of 40 hours of driving lessons (30 hours for automatic). The less talented ones will definitely need many more lessons, this depends on the person.
Apart from being able to "drive", you must of course also take a practical exam.
Here we are faced with the administrative restriction of a mandatory 5-month practice period, starting from the start date of the provisional driving license, before you can take the driving exam.
So if you want a crash course and subsequent exam, it is best to start the course after a period of 4 months of provisional driving license. By the time we reach the 5 months, you will have been able to take sufficient lessons, and you can go straight to the exam.