Custom Summary Number Alerts

I'm currently using a custom summary number that has been configured using the CONCAT function on a standard table which points out the overall spend for a specific client for the previous day and then says what the total spend for that client currently is.

I want to set up an alert which will just share the contents of the summary number every morning so that we can more easily keep track of spend.

It won't allow me to create an alert and gives me a message saying that there are no alertable metrics found on the card.

Is there any way for me to setup the table to make an alert for my custom summary number?