Well the concept of understanding assets is important here.
Assest are config that you define and use based on the Orchestrator definition.
When you define an asset in Orchestrator , to allow REF to fetch it we define the name in Assest sheet in Config.xlsx.
There is no concept of assets from excel and asset in Orchestrator.
We you want to get a property to be kept in the Config.xlsx you can define it in the Setting tab and it will behave like a local Text asset whose value you can fetch from the excel instead of going to orchestrator.
The fetching will not use any Orchestrator activity so it will not error.
You can see the documentation here:
Ask if you have any doubts