Basic steps

Navigate to Scored Events and select Team Scoring for your Relay Event:

Select "Relay" here then decide if team members share a bib. Teams can have a single Team Bib which they'll share, or they could all share the same individual bibs, or they could have bibs that vary. We support all of those configurations
Next, click save:

Next, confirm the deletion of the default reports that were created when you first saved this as a non-relay event. The system will create a new relay-specific default report for you.

Next apply the team scoring rules you have set up (for relays, it's just whether or not the members of teams share a bib) to all available Team Types.

Now save Scored Events:

And if you head over to the reports area you'll see a new relay specific default report set up for you: