I had a nightmare with this today, been working on it since this mornineg 🙁
After installing it on my localhost I saw that the plugin code had a Russian explanation, so I thought I would translate it with Google - all fine until I went through your list of steps.
When I tried saving a document it always threw a PHP error 🙁
So, onto the live server, installed from scratch, everything worked.
Deleted everyhting for Evosearch on my localhost, uploaded to the live server and re-installed, still didn't work 🙁
So went back to localhost, removed all the text in the plugin, except the call, and bobs your uncle, it worked 🙁
Translating Russian tech is yet again a stress factor.
Now that I have it working, I can't seem to get it to sort alphanumerically, even though it is set up to do so:
I also notice that it disregards Doclisters:
I have it setup on all other Doclister calls and wanted it here as well, but doesn't seem to work 🙁