My husband is stil waiting for his ARC so I don't have a specific answer to your question but I found this in in the OP1
From Operation Manual http://www.cic.gc.ca/English/resources/manuals/op/op01-eng.pdf
(page 38)
In addition to an ARC, applicants from visa-required countries require a TRV, while applicants from visa-exempt countries require an electronic travel authorization (eTA). For permanent residence applicants, officers should note in the Remarks block of the Confirmation of Permanent Residence [IMM 5292B] that authorization to return to Canada was granted [A52(1)]. All applicable cost recovery fees must be paid prior the issuance of an ARC.
Officers should
make two copies of the original IMM 1203B form;
give the original to the applicant;
send one copy to the office that removed the applicant from Canada;
send the second copy to the Microfilm Unit, Records Section, Information Management and Technologies Branch (BIM), IRCC, NHQ;
inform applicants that they must present the IMM 1203B form at a port of entry.
If applicants arrive at the port of entry without an IMM 1203B form, they may be reported under subsection A44(1) for non-compliance for not having obtained the authorization to return to Canada as required under subsection A52(1).
Note: The ARC document should be used to grant the authorization to return to Canada whenever written authority is required (including exclusion orders). Its use is not limited to previous deportees where the PREV.DEP flag is enabled.
From what I read it looks like the authorization to return is noted as approved in the COPR (confirmation for permanent residence). My understanding is that visa exempt countries get the COPR in the mail (probably certified mail) and for people that need visa to Canada the Visa office requests the passport so they can insert the COPR in their passport, just like any other visa except in this case is a COPR.
The Operation Procedure manual (OP1) is very helpful to understand a lot of the questions we have regarding the ARC.
One of the forum members Jimmy64, was recently approved for his ARC, and last I know he was waiting for his passport so maybe he can give us a bit more information once he receives it.