How do you study?

Hi! I took a big career test the shrm-cp and failed I am devastated I studied hard but idk where I went wrong. When I took my test at times it was so hard me to focus the paragraphs that kept coming the more I felt like my brain just gave up on me. I did the ADHD testing and my results are coming soon but they already told me it prob is ADHD. this has been a life going think. I just wanted to be able to retain information and actually don’t blank or can’t focus on tests anymore any advice will help!

Thank you