Flow is far from perfect. And when you need the group-id to run scripts to make changes to Teams or Groups there is no action to do so. With a little knowledge of how to set up an Azure application and how to use graph inside a flow you will be able to get the group-id with a short request.
With this short graph request you receive only the id in return. With the filter argument you can search for the group alias. Now you can convert the Json-response back into a flow variable and use it in your Azure Automation scripts etc.