Gents, thanks for your responses.
The working method for myself (but not for Chrome oddly) is to do the following in AFDS:-
Open new record for Replying Party Trust (below)
Selecting option 1, enter the addresses as shown and then save the defaults.
I've the downloaded (User/Device/Live etc) from the SSO page but they didn't work properly for me.
Anyway, this may be useful for somebody else.