Congrats on earning your Divemaster certification.
The PADI AI Course is essentially the first part of the PADI Instructor Development Course (IDC). The second part is the OWSI Program.
During the program, you'll learn about learning and instructional systems, how to teach confined water, knowledge development and open water sessions, and how to organise and conduct the programs that an AI can run, such as PPB and Project AWARE Courses.
You'll gain hands on experience in conducting those teaching sessions, and you'll further refine your dive skills.
Some people choose to do the AI Course, and then later do the OWSI Program before going onto the Instructor Exam (IE). This approach is used when people want to gain experience, and also take a little more time.
Others choose to do the IDC in one go, and then do the IE.
Hope this helps.
Cheers
Des