Your question is somewhat broad, and answerable, but this answer should not be considered as providing advice. Your question may have gone unanswered for two reasons. First, people may not know of the available resources for obtaining a copy of your book of interest for review. And second, nobody wants you to have a bad experience based on what happened after following a recommendation that was given. Of course, nobody wants you to have a bad outcome. You have to take responsibility for making the effort to achieve success.
You have indicated you have no essential background in calculus, and that this is a somewhat new beginning in trying to learn the material. One caution, though... Take your time. If you do not have a pre-calculus background of knowledge, you may do well to review all of that material first. Are your skills ready for calculus? The usual prerequisites are algebra I and II, geometry, trigonometry, and precalculus or math analysis. Having background knowledge in analytic geometry will also be helpful and this is usually part of the precalculus series of topics. Make sure you know these prerequisites first. The usual requirements for entry into calculus are successful grades in prerequisite courses, first. If you are uncertain about your readiness or skills, ask for some guidance from the folks at your guided course of instruction. Or ask for help from other professional resources, such as your school math department, or counselor. You will find that having at the ready reference texts for each of the prerequisite subject areas, will be helpful in refreshing your memory and retaining your skills when you have a question about something basic that you have previously learned. There is an old saying that the mark of a good education is not what you have learned, but what you have forgotten. Consequently, for those courses and your studies in calculus, keep all of your notes and worked problems!
A suggestion would be that you review the College Board requirements of the AP course, here as the information is complete regarding supporting texts and material covered in the tests. The text list they give does not include the Stewart 9th edition text of interest, but nevertheless, does mention several preceding editions, including Stewart, Calculus for AP, which may be of interest. A complete sample syllabus of AP required material may be found here. This AP syllabus is one of four various syllabi using different texts, however this syllabus does not use the Stewart text. Nevertheless, the covered material will be the similar, syllabus to syllabus, and this syllabus is an excellent guide.
The Stewart 9th edition text was given a cursory review, and was found to comprehensively cover material in calculus up to, and including an introduction to differential equations. Of particular note is that the book has many fine illustrations and apparently very complete examples that support the subject material of each chapter. Problem sets are numerous and odd-numbered problems have answers provided at the back of the text. The index is complete. Each chapter has sub-topic study guides and overviews to assist the student in reviewing and keeping in mind essential background information.
Given that you can obtain and review the book at no charge, and that you can access a syllabus for the AP course, and further that you may be using a guided course of instruction, you may be ahead to download the Stewart text and begin a review of the material.
One final thought: If your guided course of study uses a different text, then that text may be best. Your guided course of study has your interests at heart in providing you with the material necessary to pass the AP exam. Asking for their thoughts may be helpful regarding the Stewart text.