If you have a custom payload format decoder at TTN (The Things Network), you can send your payload variables directly to TagoIO.

To display locations on a Map, your data needs to be sent inside the "location" field with the format showed below:

{
  "variable": "speed",
  "value": 10,
  "location": {
    "lat": 42.2974279,
    "lng": -85.628292
  }
}

TagoIO already converts your latitude and longitude variables to that specific format, so you don't have to worry about any conversions. In order to accomplish that, you need to have the variables latitude and longitude or lat and lng, and TagoIO will automatically get these values variables and create a new variable called f_location.
To rename that variable, read this article`

After you get your device sending the latitude and longitude to TagoIO, create a dashboard and add a Map widget.

When selecting the variable, choose your device and select the variable f_location.