I want to set a field on the customer record by concatenating a field value to a string (to create a url value). How may I do this in a WF? Would I need to use the formula and set it to something like this: {"https://test.com/"} + {customer_id)

If the part before the field value is the same for everyone, you don’t even need a workflow for this. You can just create a custom entity field of type Hyperlink, and set the default value to:

<https://test.com/{id}>

CONCAT(‘https://test.com/‘,{customer_id}) or

thanks, both. i ended up using a hyperlink field and that seemed to work.