You will need to install the Securly SSL certificate on your device to ensure that Securly is able to filter all HTTPS sites browsed there effectively.

Note that the latest update to macOS Big Sur does not allow the SSL pkg to work for all browsers equally. While you can use the following process to push the package to trust the certificate in Firefox, you would need to push it as a configuration profile in your MDM for Chrome and Safari.

Automated installation process

You can automate the installation process via MDM by downloading the ‘Securly Certificate Installer.pkg’ file at the end of this article. After downloading the executable, follow the steps below:

Navigate to the executable you just downloaded and double click it.
You will be presented with an installation wizard.
Continue through the installation steps by clicking "Continue" through each "Introduction, Destination Select, Installation Type, Installation, Summary".
Click "Install" and enter your System Administrator password at the "Installation" stage.
If the installation is successful, you'll be presented with a "The installation was successful" message with the executable window.
To verify that the 2034 SSL Certificate has been installed successfully, you can navigate to "Keychain Access" and look within the "System Keychain" Folder for Securly SSL Certificate.

Manual installation process

To manually install the Securly SSL certificate:

Download the Securly certificate CRT file. securly_ca_2034.crt
Search for Keychain Access in Spotlight search, then press Return.
Select "System" in the left-hand column.
Open File > Import Items or drag and drop to import the certificate files into the "System" keychain.
If you’re asked to provide a name and password, type the name and password for an administrator user of the computer.
The certificate should now show with a red X. That means it is entrusted. To provide trust, double-click the *.securly.com certificate. Under "Trust", change the setting at the top (When using this certificate) to "Always Trust". The GIF is pictured 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 .pkg file that can be used directly on a Mac.

How do I install the Securly SSL certificate on macOS?