You must add this mod to your library from a device that is not your XBOX to see it on your Xbox. There is a list on the left side, scroll to the bottom and you will see WIP, add your check mark, now search again and it will show up. If you search workshop plus you will not return any results because it is in the WIP section and is partially hidden.

Lets say it is too hard for you to transfer that link and you just want to search for it. Use the link provided above and you will go to the correct page then click add to my library or favorite it, both ways work and yes you can do both.

Go to BethNet on a different device and you must sign in and that account must be linked to your Xbox. You must go to BethNet on a separate device. First thing to understand is you can't get access to any WIP or that section from your Xbox even if you are using it as a browser. I took screen shots so I could explain this a long time ago, they are on another computer. Click to expand.It will show up but it is not easy.

Fallout 4 hidden wip mods