In order to install an SSL certificate on iPhone/iPad, you need:
- iOS 12 or higher version
- Safari browser
- Configured IMAP/CalDAV/CardDAV or Exchange ActiveSync account
- Open your Webmail in your Safari browser.
- Tap on the Integration with device link.
- Select the SSL certificate option. Enter your username and password if prompted.
- Tap Allow to download the profile.
- Tap Close once the profile is downloaded.
- Open Settings and tap on Profile Downloaded. Tap Install.
- Enter your passcode and tap Install twice.
- Tap Done.