Aid4Mail cannot read or write OST files natively. Aid4Mail can only process an OST file if it's connected to a MAPI profile (Outlook or Exchange account).
In this case, you'd need to use the "Email profile" option on Aid4Mail's Target Format or Mail Source screen.
Should you require any assistance, please don't hesitate to contact the help desk.
If you would like to buy an Aid4Mail license please visit the Aid4Mail website.