First through the Avast Store website and I just tried that link. Both didn't work. I'm using Windows 10 (x64).
Did you use the custom install selection when you installed? Did you select to install Passwords (old)?
If not, open App and Features via a right click on the start button next select to uninstall Avast
next select Customize when that option opens make sure you select Passwords (old) and finish by selecting
the Customize button to start the process.
Reboot the system.