How do I tell Lr to read my Lr library on my external harddrive?

As has been explained by others, the Lightroom desktop app requires that a catalog, with previews/proxies, is stored locally (if it wasn't, performance would be abysmal). That local catalog and associated data is always stored on the main system drive (different locations depending on which OS is being used), and cannot be changed. Yes, you can move it to a different drive, but Lightroom will ignore that and simply recreate it again on next launch in the same default location from the master catalog in the cloud.

So, you can delete those copies that you made on external drives, they're just a waste of your disk space, then use the % amount on the Preferences>Local Storage tab to govern the amount of space that Lightroom is allowed to use on that system drive.....but there's always going to be a minimum amount of space needed.

One other thing to note is that Lightroom also stores local copies of some original files, even if the Preferences option to "Store a copy of all originals at the specified location" is unchecked. Images you import either from hard drive or camera memory card are always initially copied into the specified location (if you don't set a specified location, they'll be stored inside that local libvrary on the system drive), and when you edit images a copy of them will also be downloaded from the cloud and temporarily stored in that specified location (or default if location is not specified). If the "Store a copy of all originals" option is unchecked, it is intended that those other originals are only stored temporarily.....however, the automatic deletion of them is subject to some complex rules which are not always sufficiently aggressive. So it's not unusual to see them hanging around in the specified location for longer than expected, so it's always advisable to set the location to an external drive that has adequate free space.

I'd also suggest you re-install the Creative Cloud desktop app, as it's that app which controls installation of your subscription's authorised apps and keeps them updated. It's meant to run as a permanent backgroud task, I recommend you allow that to happen.

You'll have to keep watching. I know that Lightroom has to keep a library on the computer. But I don't use Lightroom enough to intelligently discuss its operation. If you keep watching there are some Lightroom (cloud version) experts that will chime in and be able to advise you. But I do know thhat you can't just have everything in the cloud. There has to be a certain files/folder that are local in oorder to make the system work.

Reinstalling Lightroom isn't going to change anything. First of all, you need a Lightroom catalog that is compatible with Lightroom Classic. If you have been using Lightroom Classic then you are ready to go. If you have been using a previous version then you will need to install the trial version Lightroom Classic long enough to run it to allow it to create an upgraded copy of the catalog you have been using. The next step is to start the cloud version of Lightroom and migrate that catalog. This process will move those images to the cloud. The images on your hard drive are simply a backup copy. The working images, they images that will use up the 1 TB cloud space that is part of your plan are the ones that will migrate from the catalog, and the ones that you will import after you have migrated.

As you import new images you can choose the option to have a copy stored on your local hard drive. I cannot give you a lot of details about that process because I primarily use Lightroom Classic. If you haven't used any previous version of Lightroom or Lightroom Classic, then the process would be to simply start importing new images. They will be added to your online collection in the cloud and, optionally, stored locally on your computer where you have designated them to be stored.

This is a very abbreviated introduction. Hopefully it will bring attention to your questions and will bring advice from more knowledgeable Lightroom users.