Hi Fez
The first part is a warning message about the ABA file's date being in the future, which the software can do, but just need to be mindful that your bank may require the ABA file date needs to be the same as the file upload date.
The 2nd part does indicate that one or more of the selected contact person have incomplete payment details, it's possible that the details were edited or new contact added since the last ABA file generation. From the error message I gather that you are using the new MYOB Business, I'd suggest selecting 1 contact or deselecting 1 contact at a time, then hit the 'Download bank file' button, if you get the error again then it means the selected contact(s) need the payment details checked, if it's giving the confirmation warning window then it means the selected contacts are fine. Keep doing so until you can locate all the contacts causing the error.