IMM5669 must be included in your spousal sponsorship application package sent to IRCC Mississauga.
After you have received AOR from IRCC Mississauga, IRCC usually ask you to upload the form in your Online Account.
But it must first be included and sent with your application package......refer the checklist 2018v for the documents and forms.
If your application is not complete IRCC will return it to you.
Spousal Sponsorship Checklist