Thanks @atma.love, I quickly tried to recreate the flow that might be causing issue for your friend here... Essentially app is not asking to signup but is asking to accept Ecency's policy, once accepted, later launches of app will open external links as expected without needing to signup.
For further improving the user experience I have added a task in our backlog to better handler first app launch in case app is opened using an external link
Aha. i understand now. My friend already had ecency app installed ( i didn't realise that) but was not logged in as he lost his keys over 3 years ago. i've now set him up with a new account.
Thanks for response