How to install a certificate on an iDevice.
support.quovadisglobal.com/KB/a64/how-do-i-install-digital-certificate-onto-an-iphone-ipad.aspx

How to install a certificate on an Andioid Device
* Click on the dowload link
* Give the cert a name in the popup window
* If you don't have one, set a PIN lock on the device (sorry)

How to install a certificate on a Windows Device
* Download the cert
* Double click it
* Click install
* Choose local machine (not prompted on all versions of windows)
* Choose "Place all certificates in the following store"
* Browse to "Trusted Root Certification Authorities" which is the second choice
* Click OK
* Next
* Finish
* Then yes/ok the rest of the way out.

How to install a certificate on a Chromebook and Linux Device
(For your Linux device make sure you have the chrome browser installed)
* Download the cert
* On the top left corner of the chrome browser select the symbol that looks like three lines
* Select settings and scroll down to and select "Show advanced settings"
* Then scroll down to "HTTPS/SSL" and select "Manage Certificates"
* Once inside the Manager select "Authorities" and then "import"
* Then browse or search for the cert (it should be in the downloads folder)
* Once selected check all of the three check boxes and then select ok
* Lastly select "done"

How to install a certificate on a mac
* Download the cert
* double click it
* Your computer will automatically install the cert
* Find the cert in your Keychain
* Click on iboss
* Change the trust to always trust
* Supply your user password