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. The installation steps might differ depending upon the manufacturer and OS of your device. This article provides a couple of different ways in which you install the Securly SSL certificate.

Pixel and OnePlus device

Download the Securly SSL certificate file securly_ca_2034.crt on your Android device.
Tap Settings -> Security -> More Security Settings ->Access Encryption & Credentials
Tap Install a certificate.
Choose CA certificate.
Locate the Certificate File: Tap the menu icon (three dots) or Install from storage to browse your device's files and locate the certificate file.
Tap on the certificate file to select it. If required, enter the keystore password.
Enter a name for the certificate and then tap OK.
You may be prompted to enter your device's password, PIN, or use your fingerprint to confirm the installation.

Samsung M32 version 11

Download the certificate.
Tap Settings –> Biometrics and Security –> Other Security Settings
Tap on Install Device Storage
Tap on CA Certificate
Tap Install Anyway
Tap Download
Tap Securly

Note to automatically install the certificate your Android device will need to have a PIN set. To set your PIN go to Settings->Security->Screen Lock

How to install Securly SSL certificate on Android device