Staying Sharp is Dull

In AARP Staying Sharp, could not “Continue” after completing the first section of any of the three Additional Tests; Non-Verbal Reasoning, Verbal Reasoning & Spatial Processing. Instead was shown an empty page (...health.cambridgebrainsciences.com/…).  Upon refreshing, then CREYOS asks to “Sign in to your secure account”.  I don’t have one, didn’t need it last time, and it shouldn’t interrupt progress between subsections!  Problem Safari on two laptops.  Deleting browser data didn’t help.  Chrome worked after deleting data but sometime received “Sorry, it appears like something's gone wrong.”  Refreshing didn’t resolve.  Going back to previous page results in CREYOS asking again, “Sign in to your secure account”.