It should come up with a blank white screen when you cut and paste the crons url, and run it in a new window. Then when you come back to the module, on the bottom it should show the amount of emails sent and the date it was done, and should show 0 emails to send. If this still is not happening, I recommend that you uninstall, and re-install the module. If it STILL does not work......do you have any email or GDPR modules installed? Maybe they are causing some sort of conflict.