"Yes, but..." Whichever program you buy, you should make sure to take the Door-Opener course first. It's the foundation principle for all the RainmakerVT courseware.
Other than that, it will depend on your situation. Within each program (Networking Essentials, Sales Master, Marketing Master, Complete Rainmaker), courses are organized as predicates. While RainmakerVT allows you to open any course in any order you wish, you’ll likely find it more difficult to understand and apply concepts that assume that you’re already familiar with predicates. To keep the length of each course reasonable, the processes have been broken up into various units. Without completing the earlier courses, you'll lack foundation for the later ones, which, as a result will be more difficult to understand and complete.
You can experience courses within your program in any order you prefer, with one exception. Within the Sales Master program (which you chose because you have a steady stream of opportunities, but need help converting a higher percentage of them), you'll need to learn the Decision Process in predicate sequence. Other than that, the course order is up to you and your current challenges. Within the Marketing Master program, you're taking a longer-term approach to create a sustainable market position to carry you for many years into the future. You'll find that, allowing for exceptions driven by your situation, the courses are listed in the suggested order.