"The layer was not created because no locations could be found. Make sure your data has valid addresses or geographic coordinates (latitude/longitude)."
The following are possible causes for this issue.
The file added to ArcGIS Online is located in a private Dropbox folder. Files stored in Dropbox can be added to ArcGIS Online only if the file is located in a public Dropbox folder. Older versions of Dropbox included a public folder; however, newer versions require the public folder to be created. The following Dropbox document describes this in detail: The public folder.
Public folders must be created manually for Dropbox accounts created after October 4, 2012.
The latitude and longitude values in the CSV are incorrect. The x,y coordinates must be within the appropriate value range before adding the CSV file to ArcGIS Online.
Solution or Workaround
The following are possible solutions for this issue.
Use the correct latitude and longitude values before adding the CSV file to ArcGIS Online. The appropriate geometry coordinate system values are, longitude: -180 to +180 degrees, and latitude: +90 to -90 degrees. The following ArcGIS for Desktop document describes this in detail: Geographic Coordinate System.