If you are having trouble accessing the puzzles it could be because you need to enable cookies, see the link below on how to do this for all browsers.

https://www.whatismybrowser.com/guides/how-to-enable-cookies/

If that still doesn’t work and you’re on an iPad and using the Safari browser, an additional step is to clear your browser cache. Follow the instructions at the link below, by either clicking in Settings the Clear History and Website Data button or the Remove All Website Data button.

https://support.apple.com/en-au/HT201265