As per screenshot above:
"Intellijel Firmware Updater’ cannot be opened because Apple cannot check it for malicious software.
This software needs to be updated. Contact the developer for more information.
I’ve had some issues with Ctrl + Open on macOS Sierra and up. Sometimes Gatekeeper still gives me an error.
You could trying going to > System Preferences > Security & Privacy > General and then click the lock icon. Afterwards, select ‘Allow apps downloaded from: App Store and identified developers’ to stop this from happening as much in the future. Also, you may see a button at the bottom right that says, “Open Anyways”, that you should click.
If nothing works, worst case scenario, you can temporarily disabled Gatekeeper via Terminal but it’s risky and not recommended. You should immediately re-enable it, after installing the Plonk firmware update, if you do windup having to disable it.