op doesn't seem to be trying to replace world map graphics though, judging from the screenshot. assuming the graphics themselves are in the right place (they can't be in an arbitrary folder) maybe the level file itself isn't placed directly inside the episode folder? don't know if that can cause any issues.
could you outline your folder structure more precisely? (maybe send a screenshot of your file explorer)
for example, if the pack had its content inside an extra folder, you can't just extract that folder and expect the graphics to work (but the pge tilesets still might, just as your screenshot shows)
if you want the changes to affect the entire episode, you put the image files
themselves directly into your episode folder, or alternatively if they're only supposed to be for that level, make a folder with the level's name (without the extension) inside the episode folder and place them there