How can my client register for MyAviva?

To register, please ask your client to visit our customer site.
They'll need to register using an activation code (if they've been sent one). Otherwise they can simply use their AV policy number.
You can find your client's AVXXXX account number by going into 'Platform Services', and generating a 'client by adviser report' under 'Business reporting'.

There's also a client MyAviva user guide.