It does not have any clear specific instructions, whether to upload online or send it:
The letter states:
Documents sent as attachments cannot exceed 5MB in size. Any attachment larger than 5 MB must be divided into smaller separate attachments.
Each of the above requested items must be received in our office by the due date listed. Failure to do so could result in the refusal of your application. Please quote your complete application number on your correspondence.
Please return this letter with the requested documents.