There is no such thing as a "must", it all depends on your score.
The higher level of your education (Master or above), the better your ILETS score (7.5 or above), the more Canadian working experience (>3 years) you have, the higher your score, making you more eligible to apply for PR.
Oh and of course, if your profession is in demand, you have a very high chance of getting PR very soon. Good luck.