How do I connect my wife's phone to AVAST premium?

I am a novice and need help. How do I connect my wife’s phone to my avast account? I have a laptop and mobile that are fine, but I cant connect hers.

Hi,

I take it you want to install the application on your wife’s phone.
Please see this guide for installation https://support.avast.com/en-ww/article/Install-One/?option=mobile
and this guide for the activation of the product.
https://support.avast.com/en-ww/article/4/?option=mobile
As a paid customer you can also contact support here: https://support.avast.com/en-au/contact/paid_pc_avast-one