To install the MISD content filter certificate on an iPhone or iPad you must use Safari to download the certificate.

MUST FOLLOW ALL INSTRUCTIONS TO WORK PROPERLY

1. In Safari, click this link: ContentKeeper Certificate to download the certificate.
2. When prompted, click "Allow" to the prompt asking if you would like to download the profile. 
3. Go to your device Settings > General > VPN & Device Management
4. Click on the ContentKeeper Appliance CA (Mercer Island) profile
5. Select Install in upper corner, then click install if it prompts you again.
6. Click Done in upper corner.
7. Go to Settings > General > About scroll to bottom then Certificate Trust Settings
8. Enable ContentKeeper Appliance CA certificate and click Continue
9. Done

ContentKeeper Certificate