When calling the snippet
TaggerGetResourcesWhere it returns only the query and don't show results of that query. I believe you have to pass parameters to the snippet call like
&tags for the querying resources having these tags or
&groups for querying resources having tags existing in that group. When no parameters passed to snippet it will fetch tags passed in the URL with GET.
To create a menu with pdoTools maybe the snippet pdoMenu is a better and cleaner way to create menus. See
https://docs.modx.pro/en/components/pdotools/snippets/pdomenu
how to tell tagger what template to use
As far as I know the template to use by Tagger has been set in the properties of the group you created in Tagger.
I am back on home page, because i dont have 404?
This is the default setting. If you want a real 404 page to show just create a resource and set the key
error_page in your system settings pointing to this resource.