You would need to install the Securly SSL certificate on your device to ensure that Securly is able to filter all HTTPS sites browsed there effectively.
To manually install the Securly SSL certificate
- Download the Securly certificate CRT file.(Link)
- Navigate to Finder > Applications > Utilities > Keychain Access
- Select ‘System’ in the left-hand column.
- Open ‘File > Import Items’ and import the ‘securly_SHA-256.crt’ files into the ‘System’ keychain.
- The certificate should now show with a red X. That means it is untrusted. To provide trust, double-click the *.securly.com certificate. Under "Trust", change the setting at the top (When using this certificate) to "Always Trust". This is pictured in the gif below.
Alternatively, you can automate the installation process via MDM by downloading the ‘OSX SSL Install Securly.zip’ file at the end of this article. The file contains a .app that would automate the process. There is also a .tar file that can be used directly on a Mac.