First on the ipad open safari (this is important will only work with this browser for installation)

navigate to :https://combemartin-sch.org/cert/

Download the certificate (above and it will prompt you to install)

Then once the certificate is installed you will need to do the following.

Trust manually installed certificate profiles in iOS and iPadOS

In iOS 10.3 and later and iPadOS, when you manually install a profile that contains a certificate payload, that certificate isn't automatically trusted for SSL.

You must manually turn on trust for SSL when you install a profile that is sent to you via email or downloaded from a website.

If you want to turn on SSL trust for that certificate, go to Settings > General > About > Certificate Trust Settings. Under "Enable full trust for root certificates", turn on trust for the certificate.

Apple recommends deploying certificates via Apple Configurator or Mobile Device Management (MDM). Certificate payloads are automatically trusted for SSL when installed with Configurator, MDM or as part of an MDM enrolment profile.

Published Date: 

Installing the Certificate Authority on BYOD devices