I fixed the issue. You should receive emails now.
Hello, I have successfully set up the plugin as you suggested. The test email has arrived successfully but the Site contact form does not arrive yet
This is a known wordpress issue. It has problems to send emails. A solution for this is to configure smtp.
This is a plugin for smtp: https://wordpress.org/plugins/wp-mail-smtp/
And here is a tutorial how to setup it: https://wpforms.com/how-to-securely-send-wordpress-emails-using-gmail-smtp/