If you are an AP member or customer with a login for another website, such as AP Newsroom or AP Images, that username and password will not work for your AP Stylebook subscription.
You need a separate login for apstylebook.com.
We understand wanting ease and simplicity, and you might not want to remember one more password. You are welcome to use the same password for the Stylebook that you do on your other AP platform, or you can use a password management tool to keep them for you.