Hi,
Thanks for using the HP Support Community.
Set up the printer first and enroll successfully to the HP Print plans on the first device.
These examples will be useful:
https://www.youtube.com/watch?v=MKdaqJqWfNk
https://www.youtube.com/watch?v=bTH-Q-8WqDM
(this example is a LaserJet HP+, while yours is an OfficeJet HP+)
After successfully setting up and enrolling to the HP Print Plan, connect the other 2 devices using HP Smart to the printer.
Hope that helps!

I am an HP Employee
Although I am speaking for myself and not for HP.
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