This ^^^.
When you arrive in Canada with COPR, you (or rather the CBSA officer) will submit your PR card application.
Some months later, depending on processing times, you will receive your PR card by post (or occasionally, you may be required to collect it from a CIC office - don't worry, that's really rare).
In the meantime, between landing and receiving your pr card, you use your passport & COPR for any formalities necessary.