@RobAC 

Hi, welcome to the community.

There are step-by-step configuration guides on the Deco APP, such as:

https://www.tp-link.com/en/support/download/deco-x20/#video

Once the first main unit is configured, the other two units will join the Mesh network automatically after power-up, as the units in the same package are preconfigured.

I think you can let him have a try first.

If you want to set it up first on your case and send it back to your friend, there would be some details for your reference:

1. You might need to share your TP-Link Account ID with him later.

2. If you didn't use the same internet network/connection type as your friends, he might still need to change the network settings after receiving the Deco.

Thank you very much and best regards.