Its in their website, the pop up instruction says walk in allowed.Oh wow. That's amazing. Do you have a source for this?
Good luck with that though- I went in for walk in BLS toronto 10am- security sent me home after 12.30 saying no more walk in. ( people were standing in walk in line from 7 am).
Try to book appointment between 8.30 am to 8.45am daily under OCI, Visa or passport category.