I found this process unnecessarily frustrating, so here is a complete guide to applying for a BOWP.
I applied for PR through Express Entry in the Canadian Experience Class while on a two year International Experience Canada open work permit, so this guide takes the route that follows on from that. If you have a LMIA, I think a few aspects will differ for you.
I applied in May 2020 and received my permit in October 2020, so this guidance is accurate to that time, and is a summary of what I gleaned from various corners of the internet (I found this YouTube video particularly helpful, and the Irish and Applying for Canadian PR group on Facebook useful for troubleshooting issues with individual forms).