Hey gang, I think I found my answer. I spoke with an Arri rep and this is what they said.
If you're using EF lenses (in my case, Rokinon primes), you would need the AMC-1 to power the motors, since there is no LBUS connector on the Alexa Mini EF mount (like there is on the PL mount).
Also, for using the WCU4 on other camera bodies (such as Epic, Sony, etc), you would also need the AMC-1.
But, from what I've also heard, is that yes, you can use the UMC-4 as well. I think the main difference between the two controllers is that the UMC stores lens data and the AMC does not.
Hope that helps! Thank you all for your responses.