When you finish filling in the report with all the information from the accident, you’ll then have to save it. When you tap the "Save report" button, it will automatically open up your prefered email application so you can send it to anyone.
Once in the email application, you can send it to the other driver or simply cancel the email.
If you decide to cancel the operation,  the report will automatically be saved in your report logbook anyway.
In case you want to send it later, you just have to open the saved draft again and tap on the "Send by email" button.