The Mapping Sheets add-on requires a sheet named Data, which holds all the information for mapping.
In your case, you can simply rename your sheet as Data, before launching the Mapping Sheet add-on in that particular Google spreadsheet.
The add-on will recognize your sheet Data as the information source for mapping. You only have to select which column you will use for Title, Filter, and Location and then Build and View as usual.
Here, we used an existing data sheet with the following headers:
Then we selected Contact for Title, Group for Filter, and Place for Location, as you can see below: