"Not knowing what they were, I un-ticked them both before starting the download. " You mean before starting the installation :-)
Yes, I unticked them as well.
"When I launch Teracopy 2.22, it shows two narrow windows, one labelled 'Drop files here', and one labelled 'Select target folder'. "
Don't bother to launch it. It automatically hooks into Windows Explorer.
When you choose to copy/paste or drag/drop files, it runs automatically, in place of the normal copy routine.
Try it:
Copy a file into a folder by your usual method (Drag and Drop, or Copy and Paste)
Copy the file again, and the Teracopy window will pop up, point out that you already have a file of that name and ask what you want to do. The second button down on the right (I think) offers Autorename All. If you click it you'll find that you now have your original file, plus another with the same name but with the suffix "_2".
Be aware that left-drag and drop uses TeraCopy Automatically.
Right-drag and drop will bring up a menu which includes the usual "Copy hee" and "Move here" options, but also "Teracopy here" and "TeraMove here".