Licence can't Be opened

Lost Avast (my fault- did a refresh).
Have had licence number resent. Can’t open -“need app to open” I’m told.
Select app which tells me to go to publishers website.
Website tells me to install program before inserting licence no. Can’t install program until I HAVE Licence no.
Ring around the rosy.
Question: How to get licence no. from resent email? Which “App” do I use?

Install the avast version you have the license for.
Provide the license to it.
https://www.avast.com/faq.php?article=AVKB7

Hi Brenda 3,

You need to install Avast first, then to open the license. The app needed to open the Avast license is… Avast 8)
Install it as a trial and then apply the license.

Or you apply the license when you install Avast! https://www.avast.com/faq.php?article=AVKB1#articleContent

Greetz, Red.