This problem has been corrected with the release of Safari version 11.0.
If you are unable to update to version 11.0 or later the following instruction are relevant.
Receiver operators who utilize Safari when accessing the Web User Interface (WUI) may experience login issues.
Solution: Install an alternative browser (Firefox or Chrome)
Safari Workaround: Check the "Remember this password in my keychain" check box.
Article ID: 849
Created: May 17, 2016
Last Updated: April 26, 2018
Author: Henry Berglund
Online URL: https://kb.unavco.org/article/septentrio-polarx5-safari-web-browser-incompatibility-849.html