Hi my name is ***** ***** to Just Answer. I am reviewing your question and will reply ASAP.
What model Nextar GPS device are you trying to update?
The recommended way to get new map data is the Naviextras site here:https://www.naviextras.com/shop/portal
There are 6 different devices listed for Nextar here:
What model is your device?
If this resolves your issue, please rate my help 3-5 stars.
If you need to ask any questions please let me know.