Catalina fails to install and not seeing any install file

Hi, I am getting two types of failing to install. The first is a verification failed message. The second is that it runs the update, goes through the black progress screen long wait with progress moving as expected. but it will boot afterwards as though nothing happened. It will then tell me there is an update available. Both cases, all attempts in-fact, are not showing any Install File in the applications directory. It's downloading something but no idea where. I have search both Libraries and general directories including the downloads folder. No sign of it. I tried to follow a how to "Download" manually, opposed to "Get" how to. But can't get to any "Download" as described. anyone know what might be going on here. Each 8gig download is using up my download cap.

• Using 2014 iMac 27" fully updated. Nothing special done to it. Used various tips on solving errors such as checking HDD.