Cannot Start Dataloy VMS from Mac

Problem

It is not possible to start Dataloy VMS from a Mac. How can this be fixed?

It is possible to access the VMS from a Mac after following the step-by-step instructions below:

Starting Dataloy Voyage Management System (VMS) the First Time - for Mac:

Open a browser and enter the Dataloy VMS URL.
Click Enter. The Dataloy VMS start page will display.
Click Start.
A file called client.jsp will download (usually to the Download folder).
Change the file's extension from .jsp to .jnlp.
A pop-up opens asking to confirm change.
Click Use .jnlp to confirm change. The pop-up will close.
Right-click the newly created file and from the menu select Open to Open Dataloy VMS.
The next time Dataloy VMS is opened – double-click the client.jnlp file.
Note: If message appears stating "client.jnlp file can't be opened because it is from an unidentified developer":

1. Go to System Preferences > Security & Privacy > General.
2. Click Allow apps downloaded from Anywhere.
  Note: Allow changes: click the lock symbol to unlock.
3. A pop-up opens asking to confirm change.
4. Click Allow From Anywhere.