Yes. Wolf4SDL is released under Community / External hub and costs nothing. Neither it nor Wolfenstein has any paid content.

What do I need to run Wolf4SDL?

Wolfenstein, which is itself free. Wolf4SDL is an add-on and will not run standalone.

How do I install Wolf4SDL?

The PlayBound Launcher installs it in one click from Wolfenstein's mods list. You can also install it by hand — full steps are on this page.

Roughly 40 MB, on top of the base Wolfenstein installation.

Wolf4SDL — Free Wolfenstein 3D via ECWolf Mod · PlayBound