At the most fundamental level, you at least need to buy a controller which produces the kind of power needed by the motor. You have chosen an AC motor, so you need an AC controller (also called an inverter); the Soliton is (as the listing says) a DC controller.I will be buying the AM Racing AMR 250-90 Single AC Motor and was looking for controller(s) that would be a good fit.
As of now I'm looking at the
Cascadia Rinehart PM150DX/DZ 150KW AC Motor Controller
Evnetics Soliton 1
Now other than the huge price difference and only based off of the spec sheets I was able to find the Evnetics Soliton 1 is the better choice, price and power.
Since I'm a newbie on this subject of controller purchases, what's the better way of judging controllers?
By the way, I believe that Evnetics shut down long ago - that Soliton listing is either obsolete, or they're still selling some old stock of controllers from a company which no longer exists to offer support.
Given recent experience of other forum members with EV West, I think they should be treated as an online source of some component specifications, but no should buy from them or expect support from them. On the other hand, if you don't understand the difference between AC and DC yet, the person you reached on the phone may have been understandably frustrated.I did try calling EVWest since they advertise all three components. I did get some info from the guy. He was very reluctant to give me any info but only offered me the answer "Go buy a Tesla."
By the way, all of the custom colour choices in the original post make it hard to read. I use the dark-background mode for this site, so the black text is black-on-dark-grey; if you just use the default colours text shows white-on-dark-grey for me.