How do I activate avast mobile premium

Hi, I’m not sure whether I’m doing something wrong. I have avast premier security for my PC and want to add my android tablet and phone. I downloaded the free app on both my mobile devices and a button on the home screen shows premier, i click and it takes me to a screen saying either I pay 1.99 per month I think or a one off fee. But it also asks if I already have a licence, so I click yes on the link it states something like it will load a screen to input the licence and update, but when I click on the link it doesn’t do anything. I logged in to my avast account and it shows only my PC as devices. Do I have to pay additionally for my mobile devices or does my fully paid subscription to premier mean its free?

Thanks in advance for your replies

The licensing is different for PC and mobile devices, i.e., the mobile are not included in the PC ones. They are different products (only that you can manage both of them using the my.avast.com portal).