Flatpak install contradiction

After believing that I had installed Flatpak successfully on Ubuntu 20.04, when I tried to install a package on it, I eventually received an error message telling me that I needed the latest version of Flatpak, ie 1.8.2. I have version 1.6.5. So I did a sudo apt update and sudo apt upgrade but still find that I am stuck on Flatpak v. 1.6.5.

So how do I install the latest version?