Hello Mats,
Thank you for contacting us.
When putting in a calendar invite from the phone, it would send out an email using the account you saved the appointment to. However, AkrutoSync does not sync, send or receive email, this is the reason why invites cannot be sent. I highly suggest to create an appointment with invitations in Outlook and not from your phone.
Regards,
Raphael
AkrutoSync