I have a family account. I want to add my wife's iphone, ipad and computer to it. I sent her the "invitation" to join, confirmed, but then she received a file that the ipad IOS (most recent version) can't read! Assuming she gets a different secret key than I have, I can't see how she can access it, and complete the joining process. Also, tried the alternative of down-loading the file to her computer, but either there's no application on it that can read that file, or I can't direct the file to the app.
A comment: your general instructions make it appear that getting this system going is a simple,straight-forward task. I don't find that to be true, and wonder if your writers are looking at this from the average user's viewpoint. The forum seems full of questions about this sort of thing. I've been a user of the stand-alone app (currently, 7.2.6) for a number of years.
1Password Version: 7.2.6
Extension Version: 18.104.22.168
OS Version: 10.14.5
Sync Type: Not Provided