You've encountered the message "We're updating behind the scenes". This message means an important update is required to continue.
Chrome automatically updates all extensions, but this can take a couple of hours depending on when Chrome checks for new versions and your browser active.
If you are unable to wait you can manually force the update:
1. Enter the following address into the Chrome address bar
2. Check the
3. Then click
Update extensions now
4. Revisit the participate test link and refresh, if the extension successfully updated you should now be able to continue.