I had the same problem, but solved it in case you are still interested.
For anyone suggesting to use the dynamic material nodes; dragging it off any material source just seems to lock the node into being for that material only; it won’t actually give us the option to select the parameter collection instead of the material.
The solution is rather easy however. It feels kinda wonky, but I tested it and it works without any errors or warnings.
What you do is place the node anywhere where it is available per default, such as in an object blueprint or something. Copy the node with CTRL-C and then paste the node into the level blueprint. If it doesn’t work the first time, just try again; with my machine I have the problem that sometimes the blueprint editor doesn’t seem to register the CTRL-C command. Anyway, doing it that way enables you to use the “set scalar parameter” node in the level blueprint as well. I reckon it’s a bug or something, since the page you linked to obviously suggested you could just place the node without having to be creative about the method.