Warning: Undefined array key “download”

Hello,

For several weeks, I have been experiencing a problem with the extension. None of my downloads work anymore.
Here is the message that appears when I try to download the file :

Warning: Undefined array key “download” in /customers/d/a/e/blog-in-lyon.fr/httpd.www/wp-content/plugins/email-before-download/public/class-email-before-download-public.php on line 167 Warning: Cannot modify header information – headers already sent by (output started at /customers/d/a/e/blog-in-lyon.fr/httpd.www/wp-content/plugins/email-before-download/public/class-email-before-download-public.php:167) in /customers/d/a/e/blog-in-lyon.fr/httpd.www/wp-includes/pluggable.php on line 1416 Warning: Cannot modify header information – headers already sent by (output started at /customers/d/a/e/blog-in-lyon.fr/httpd.www/wp-content/plugins/email-before-download/public/class-email-before-download-public.php:167) in /customers/d/a/e/blog-in-lyon.fr/httpd.www/wp-includes/pluggable.php on line 1419

Do you have any leads to help me solve the problem?

thanks

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