How to Install Flatpak Linux Mint 19 LTS

Setting Up PPA

2. 2. Enabling Flatpak Repo

   Then to Add Flatpak Repository for Mint
   Execute:

   sudo add-apt-repository ppa:alexlarsson/flatpak

   And then to Refresh Apt Repos:

   sudo apt update

   Authenticate with the User Admin Pass.
   If Got “User is Not in Sudoers file” then see: How to Enable sudo.