Sample Character Unable to Move

Some of the packs are shipped with the deprecated settings for movement input. It was never meant to be used in production setting and serves simply as an example from the old Third Person Sample. From 5.4 and up new way of setting up movement is Advanced Input plugin. Most packs actually come with all of the required files included. The best advice here we can provide is to look up relevant guides about it. Brief explanation on how to set it up: First, set the mapping for your Player Controller:

And then set up the movement similar to this (this is not the best example tho):