As this is your initial setup, the Admin password is empty. You must run the resetPassword.php script from the command line on the webserver
in the DOCUMENTROOT/weewx/divumwx/admin or DOCUMENTROOT/divumwx/admin
directory and set the initial password. To do so, when you are in that directory, issue this command: php ./resetPassword.php
This is done to protect your dashboard on initial installation. The modal will cycle when closed until you do so.