The way I achieved this was to do the following:
Select your firewall page.
Click on ‘Allow an app or feature through windows defender firewall’
Scroll down to bandlab assistant. exe & highlight with a right click.
Press the change settings button at the top right.
Then toggle the box under the column ‘ Private ‘ to on. ( With a tick ) & press ok.
From your downloads folder find bandlab-assistant-windows-latest
Right click & Run as administrator.
Try the installation process again.
Might have been a fluke but worked for me.