There are actually two errors occurring in this error message. The first is "The Address could not be validated. Update address or set the components manually" and "A Canadian Mailing address needs a postal code"
The first error "The address could not be validated..." is because the user incorrectly put in the address. In the example provided they put Drive instead of Dr, Drive is not accepted by the system and causes the field to not validate.
If you users are not sure how to properly format an address they should use the validate button, the [...] button at the end of the end of the address line. Selecting the "User Validated' check box enables the fields to be edited, they can then enter the information in the individual areas and press Format after, this will put the properly formatted address in the "Street Address" field.
Because they got that first "The address could not be validated..." error it did not save (it can't save because it is not formatted correctly), an thus the Mailing Address Postal is empty. If it saves properly then you wouldn't receive the second part of this error.
If a user completely forgot an address they would only receive the second error, this is enabled to ensure at least a mailing address is filled in for a student.
If your users continually get this combination of errors I would recommend they always use the validate button to fill in the Street Address information.