Domain mapping , after making sunrise and wp-config changes

In the domain mapping section of the multisite tutorial, I followed the instructions to (1) copy the sunrise file from the plugins folder to the content folder and (2) modify the wp-config file. When I return to Setting > domain mapping, my browser is redirected to:

https://www.adamsblogtools.com/wp-login.php?redirect_to=https%3A%2F%2Foureventnotes.com%2Fwp-admin%2Fnetwork%2Fsettings.php%3Fpage%3Ddomainmapping_options&reauth=1
instead of showing me the screen I am supposed to see with the error message gone. Help.