Thanks, Burgress, for the file.
The Displacer needs the information to work, and this information can be a simple Color Shader in the Shading Tab options. In your file there was no entry, so no data to work with. Let me know if you need more input to get this working.
The fields itself work like Photoshop [Ps] Layer. Except, there is no Freeze option in Ps. The Freeze stores the values. (This is optional, not always needed nor wanted.) If a layer above it is set to Max, this will be added. If the Freeze is set to grow or average, the newly added values from the layer above will be added to the already available information. Then averaged or grow will happen to that specific information.
In the presentation, he uses a Restriction Tag to limit the influence area of the Displacer Deformer. This is all fine, but you can use the Weight Tag directly in the Falloff of the Displacer. Try both ways, of course.
I have five files set up for you, each a little bit different. Before you change anything, have a look at the scene-file while the play-head is moving. Then switch one part off and on again to see the change. If something is not clear, please ask. If it is clear, go to the next.
Scene files, based on your file above:
https://www.amazon.com/clouddrive/share/q36pnGgoA7WmTceNgPgkm5rt60x7Gty8sdX4gHxb0oX
So far, I have too little to go on, to be more supportive, but with each question, I might pinpoint what you need to feel confident about setting them up.
I would suggest to check out this series.
First, just have a look here:
https://www.cineversity.com/vidplaytut/demystifying_cinema_4d_fields_where_can_we_use_fields
This should give you a solid base for any Field related work.
You can then check this knowledge here and practice along with him
https://www.cineversity.com/vidplaylist/morphing_objects_with_volumes_fields
To see how much you can master this, here is an advanced series.
https://www.cineversity.com/vidplaylist/growing_structures_branches_and_veins
Yes, this is a lot, but think of this as a three-segment course to master this Field (pun intended)
In any case, ask if you got stuck, or if you got stuck, go a few steps back where you felt comfortable, typically a moment later is the missing piece of information.
ENJOY