When pressing on the send email button, nothing happens, no email is mounted.

The mobile device needs to have an email account set in the native Mail App. Third party App like outlook, aol and the likes do not support such export functions.

Apple, the App is called Mail:

https://support.apple.com/en-ca/HT201320

Android, the App is called GMail:

https://support.google.com/mail/answer/6078445?hl=en&co=GENIE.Platform%3DAndroid