This really should be along with your original topic -
https://forum.avast.com/index.php?topic=319949.0 as more information is in that topic. If it is related, this just duplicates effort by those who tried to help.
Given that you are posting in the Avast Secure Browser sub-forum (this and your other topic).
If you are trying to run Avant Browser under the Avast Secure Browser function ?
If so it may be that Avant Browser isn't supported by ASB.
I don't know and can't really test as I don't Use the ASB nor do I have Avast Browser installed.