Web Farm Framework - Missing IIS features

That's Application Request Routing. Install it as well.

As a note, you might need to nuke your farm configuration if there are problems layering it atop the existing installation (which I assume is on a controller).

App Request Routing is the proxying module that integrates with Web Farm Framework, which is the Server Farming and app and platform provisioning module (as of WFF 2.0; WFF 1.0 was literally just "these servers exist in a farm, are online/offline, and here are their IPs").

ARR installs WFF 1.0 if you just install it; WFF doesn't install ARR if you install it, but ARR integrates nicely on a WFF Controller.

Use Control Panel -> Administrative Tools -> IIS Manager, not Server Manager.