How do you apply a marketplace animation to a character?

Wes’ skeleton assets tutorial is still relevant

Under the presumption your Skeleton is the same as the marketplace Skels re-targeting is pretty strait forward. If it’s a different skeleton, then it can get pretty complex, but it’s still doable. Note: you may still have to modify animations a bit if the skeleton proportions are different.

I’m struggling to add this new animation I bought from the marketplace. I’m trying to add this simple walking animation for a character but to no avail. I can’t seem to find a source online that fixed my problem. Does anyone know a good brief description of how to apply one?