You are on Windows 10 but request a skin pack of 8.1. Doesn't make any sense to me. However moving on this is a Stardock related software site.
Skinpack software hacks the system and it's also needed to do skinpacks. My guess you won't get any takers for your request here. However just type skinpacks in Google if you didn't do that already and you will receive plenty of information.
If you haven't checked out Stardock software you should. It may fit what you want. Start 8 and Windowblinds are available here.