Is there a way to configure ClickSend Done Right to send from a shared number?

I am using the ClickSend Done Right plugin from Zeroqode to send SMS, and I would like it to use a shared number for international SMS. However, when I use the Send SMS (Action) workflow, and leave the FROM field empty, the message is sent from a null number instead of a shared number.

How do I tell the plugin to use a shared number?