Secureline Sub via Avast One - Possible?

I had Secureline VPN and another different free antivirus.

I am wanting to use the avast free antivirus due to firewall issues after an update on the other.

I uninstalled everything (as it wouldnt install Avast Free until I did) and installed Avast One instead. I logged in hoping to be able to use my sub for the firewall, yet it is still only showing the free limited VPN.

I have tried to reinstall Secureline VPN alongside yet the window vanishes after installing and it never actually appears on my laptop, even after a restart.

Any ideas? Thanks.