In this case - if you have installed some other competitor AV - than you CAN install Avast Secure Browser!
"Amazing", Avast gives ability to install with other AV and blocking with his own business AV
However. I do today an usual madness trick:
- uninstal ABA client
- install Avast Secure Browser. Yes - it installed and works!
- install ABA client again and Avast Secure Browser works now with ABA
But sysadmins won't be do such things on many PCs of firm. Because time=money. As a result, Avast loosing his own base of Business AV to install his new browser.