Errors and Cannot Access Dashboard

I am getting numerous errors that seem related to the plug-in. I had not resubbed, but I was not having any errors last week. Came into these messages this morning:

Warning: Declaration of Cmpopfly_Walker_PostDropdown::walk($elements, $max_depth) should be compatible with Walker::walk($elements, $max_depth, …$args) in /home2/custompa/public_html/wp-content/plugins/cm-pop-up-banners-pro/shared/functions.php on line 478

Warning: Cannot modify header information – headers already sent by (output started at /home2/custompa/public_html/wp-content/plugins/cm-pop-up-banners-pro/shared/functions.php:478) in /home2/custompa/public_html/wp-login.php on line 496

Warning: Cannot modify header information – headers already sent by (output started at /home2/custompa/public_html/wp-content/plugins/cm-pop-up-banners-pro/shared/functions.php:478) in /home2/custompa/public_html/wp-login.php on line 512

Warning: Cannot modify header information – headers already sent by (output started at /home2/custompa/public_html/wp-content/plugins/cm-pop-up-banners-pro/shared/functions.php:478) in /home2/custompa/public_html/wp-includes/functions.php on line 5946

Warning: Cannot modify header information – headers already sent by (output started at /home2/custompa/public_html/wp-content/plugins/cm-pop-up-banners-pro/shared/functions.php:478) in /home2/custompa/public_html/wp-includes/pluggable.php on line 932

Warning: Cannot modify header information – headers already sent by (output started at /home2/custompa/public_html/wp-content/plugins/cm-pop-up-banners-pro/shared/functions.php:478) in /home2/custompa/public_html/wp-includes/pluggable.php on line 933

Warning: Cannot modify header information – headers already sent by (output started at /home2/custompa/public_html/wp-content/plugins/cm-pop-up-banners-pro/shared/functions.php:478) in /home2/custompa/public_html/wp-includes/pluggable.php on line 934

The page I need help with: [log in to see the link]