Unable to install on second device in spite of multi-device subscription

I have a SecureLine VPN multi-device subscription active on a Samsung A14 phone. I also have an Avast antivirus and Cleanup Premium on a Windows laptop. Since I wanted to install the VPN on the laptop, I opened my Avast account using my email address on the laptop, which naturally shows my Cleanup subscription and not the phone’s VPN subscription which was purchased using the phone number. Could you please advise how to 1) install the VPN on the Windows laptop using my existing multi-device subscription, and 2) if possible, merge the two accounts into one? I would really appreciate your help.