PrimevalSeeker
Explorer
After taking a second look at the PHB Ranger and the UA Ranger, it seems that they both gain subclass abilities at 3rd, 7th, 11th, and 15th level, with the only discrepancy in the way the two versions handle their subclasses being at 5th.
So the easiest way to handle making a Ranger subclass that works with either the PHB version or the UA version is to design it with features for 3rd, 7th, 11th, and 15th level, then include a sidebar that explains that this particular conclave grants Extra Attack at 5th level if you're using the UA variant.
I'm pretty sure the only reason Extra Attack is tied to subclass instead of being a base Ranger feature for the UA Ranger was so they could give the Beastmaster Coordinated Attack instead.
Why not keep the extra attack at level five for the ranger and change it at a later level within the beastmaster subclass, while giving the other subclasses a different feature.
It seems counter intuitive that a single subclass should dictate the design of the main class and the remaining subclasses.