In case you have old police certificate within 6 month before the date of your departure they will accept it once you submitted it but if you dont have one so you have 2 options : one to authorize someone to bring this certificate for you incase your problem not with government directly or the second option need to submit LOE to them explaining the situation and that you are refguee you can't contact your country and no police certificate before 6 month of departure.this things will increase the application processing time little bit because need officer reviewing to procced the next step without this certificate.you are good and dont worry.
