My initial aim was to make a map in ArcMap where the traffic volume of Austria's highway is displayed. I couldn't find any data for that. Instead I found data for Vienna. It is a shp-file that consists of points. When I added the data to a blank map in ArcMap I get a warning, saying that the data I want to import is missing spatial reference (see in the attachment)
Above you find the link for the data i wanted to import.
How can I make a spatial reference based on the address of the single points?