Step-by-step – Arduino IDE Ubuntu 21.04 Installation

Installing

2. 2. Setting Up Flatpak

   How to Setup Flatpak on Ubuntu 21.04

   Flatpak Ubuntu 21.04 Installation Guide

   Flatpak Ubuntu 21.04 Setup

3. 3. Installing Arduino IDE

   Then to Install Arduino IDE Flatpak App on Ubuntu 21.04
   To setup the Repo play:

   flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo

   For further Insight see the Flatpak Official Documentation.
   And after:

   flatpak install https://flathub.org/repo/appstream/cc.arduino.arduinoide.flatpakref

   The Flatpak App Setup do Not need the sudo Command because then it Runs confined into a Sandbox.
   However, you’ll be Prompted to Authenticate with your User or Admin Pass.
   Then Confirm the proposed Setup with ‘Enter’ and wait until the App is Downloaded and Installed.