I mean to connect from my Ubuntu 20.04.05LTS to a Windows machine with TeamViewer. I have just installed the .deb for TeamViewer. It only shows as TeamViewer Host, and when I launch it, it doesn't look like I was used to.
I don't see how to use it as a client, where I can simply enter the information for the server and connect to it.
Is that possible? How?
Download and install TeamViewer Remote
It looks like you have installed the TeamViewer Host. Uninstall it. Go back to the TeamViewer Download Linux page. You will see something like:
Download and install the TeamViewer Remote for Linux. Do not download the TeamViewer Host in the bottom half of the page. I have crossed it out in red.
Personal Opinion below
I personally like AnyDesk as it has a smaller footprint and works very similarly, but either will do the job as long as the Windows machine has the corresponding app installed.
Hope this helps