To submit entries to the Awarding Organisations, you need to generate and download an Entries File.
There are three reasons why you won't be able to generate an EDI file.
Your centre number isn't set up
You'll need to add this into the slide over.
You can also see how to do this here: Set up and customise your exam centre
The student's Sex hasn't been added
You will need to go to the student's profile and record their Sex.
You can see further details here: Sex, Gender and Gender Identity in Arbor
A student hasn't been given a UCI
You can see how to give them a UCI here: Unique Candidate Identifiers (UCIs)