If you haven’t yet purchased your access code you can use the 14 Day Free Access option when you register with Pearson.
Be sure you are using Chrome or Mozilla Firefox as your web browser.
Be sure to clear your cache: https://support.pearson.com/getsupport/s/article/Deleting-Browser-Cached-Files-and-Cookies
Still having trouble? Open support ticket with Pearson at https://support.pearson.com/getsupport/s/.