That should normally be OK for the avastUI, but the installation screen has been larger than the UI. I have been banging on about this for years the installation screen needs to be resizeable or much smaller.
Are you running your display settings higher than 100%, right click on an empty part of your display and select display settings. Hover over the slider in the Change size of text, that will tell you what it is. If higher than 100% try dropping it back by 10% and see if that is enough.