Faced a similar situation. All you need to do is upload a document addressed to IRCC, mentioning that the HK Certificate of No Criminal Conviction requires an official request letter from IRCC and will be sent directly to them. This will enable you to complete your application and submit your eAPR. Once your application is processed and you will get your AoR. Post that after a 30-35 day period you should ideally get an update of "Medicals Cleared" and an Additional Document Request (ADR) requesting a HK Police Clearance. In the meantime, you should arrange to get official fingerprints from the police authorities wherever you live. They are a pre-requisite for the application to HK police department.
Hope this helps!
Hey... Thanks a lot. That helps. Got another question for you. While sending the requisite documents to HK police dept, is it required to send the original HK ID card or a photocopy of that works?