It is strange 'cause RPG Maker generator should grab all images by automatically. The easiest way to properly install the gen parts is to extract Generator folder into the RPGMX folder. For example, extract the Generator folder into C:\Program Files\KADOKAWA\RPGMV (not to C:\Program Files\KADOKAWA\RPGMV\Generator) folder.
If you extract all files manually, then be sure that you've put ALL files from archive into the right folders. If I'm not mistaken, you'll not see a new parts in the RPG Maker generator if you forget to extract files from the Generator\Variation\Male sub-folder.