Blend on medium for 60 seconds, then on high for 30 seconds.
After blending, pour your coffee into a cup and try it. If it's too thick, add it back to the blender with just enough water to thin it out to your liking. If it has little pieces of macadamia nuts in it, add it back to the blender and blend longer until the consistency is smooth.
Notes
What to do if you don't have a high-powered blender: I used my trusty Vitamix to make this coffee, which does a great job of liquifying whatever I put in it. If you don't have a high-powered blender, you have two choices:
Blend longer.
Soak the macadamia nuts in water for 30-60 minutes before making the coffee. When you drain the soaking water, you'll drain off the salt, so you may need to add a pinch of salt to match the flavor of unsoaked macadamia nut coffee.
Recipe inspired by Pinch of Yum's Cashew Coffee. (Cashews are high in carbs, so macadamia nuts are a much more keto-friendly choice.)