You’re right, I have it installed.

I have 3.42. Choose a file, select it (check) and press the copy/move icon, in the popup dialog the lower right choice is ‘Via WiFi’.

Now it is integrated in the base app, no more need for plugin.

I also use Total Commander, latest versions also include WiFi Web download for easy transfer for other devices. Ghost Commander also seems nice, going to use it for a bit.