This question is probably best for Squared Up Support.
However, I can tell you that this method is not correct - No xml files are used by version 3 of Squared Up, only json, and a Dashboard Pack contains a different folder structure to previous dashboards.
The migration tool also has some switches that need to be applied, you can find these in the readme.txt contained in the zip, along with the migration tool.
The method I used is only for V2 dashboards for Version 2 SquaredUp.
To input the View.json into a Version 3.0 SquaredUp, I have put the View.json in the "C:/inetpub/wwwroot/squaredupv3/user/packages/everyone/dashboards" path and recycled the App pool.
This has brought the dashboard in to V3 as when I do a global search for the dashboard name , I can find it but I still cannot see it pop up in the Menu and neither under "More" tab.