Be sure to read the system requirements prior to downloading and installing EncodeGUI.
EncodeGUI macOS requires a special installation method (app hasn't been notarized by Apple):
1. Open the EncodeGUI_v1.2.3_mac_setup.pkg file, and you will get the error "EncodeGUI_v1.2.3_mac_setup.pkg can't be opened because Apple cannot check it for malicious software" when you try to launch the file (I have a developer certificate from Apple, just no notarization on the app).
2. Go to System Settings > Privacy & Security.
3. Scroll down until you see: "EncodeGUI_v1.2.3_mac_setup.pkg was blocked from use because it is not from an identified developer."
4. Click "Open Anyway" right below that message and enter your system password to confirm the changes.
5. The EncodeGUI installer will load and now you can use the software without restrictions.