Question about Washington ADU law

[Joshua Peglow]

My wife and I have been looking for an investment property in WA. We live in Bremerton but it’s difficult to find something that cash flows. 
We found this place in Ellensburg that looks interesting.

https://www.zillow.com/homedet...

If I’m understanding the ad correctly, it has two separate rentals on the property besides the house. I’m not familiar with Ellensburg. Would it be legal to buy the house as a rental while also renting the other two or does it need to be owner occupied. In Bremerton I believe you must live in the house. Do these things vary by county or is it usually state law? Thanks in advance!