Linux DolphinBar problem

Hello, as the title says I have a problem with my dolphinbar when I try to use it on linux:

I have already tried this tutorials (and every tutorial linked by them):-https://forums.dolphin-emu.org/Thread-mayflash-dolphinbar-on-linux, https://www.reddit.com- /r/DolphinEmulator/comments/c5cgo1/how_do_you_make_the_dolphinbar_work_on_linux/

But I could make it work 2 things that this posts says:
- start dolphin from root:

$ sudo dolphin-emu sudo: dolphin-emu: command not found 

- install dolphin from the official guide:

$ sudo apt-add-repository ppa:dolphin-emu/ppa Unofficial builds for Dolphin Wii/Gamecube Emulator. Install the dolphin-emu package for the latest stable release of Dolphin. Install the dolphin-emu-master package for weekly builds that include the latest upstream changes from git. The dolphin-emu-triforce package will allow you play Triforce games, as well Wii/Gamecube games. It's based on the old Triforce fork (4.0-315). You'll need to enable the Universe repo before install Dolphin. For Ubuntu 12.04 and 14.04 users: dolphin-emu needs an updated libstdc++6 (>=4.9), so install this PPA first: https://launchpad.net/~ubuntu-toolchain-r/+archive/ubuntu/test It will update libstdc++6 in your system, so be careful. For Ubuntu 16.04 users: A bug in the version of glibc shipped in Ubuntu 16.04 causes a performance regression in Dolphin. To work around this, upgrade to Ubuntu 16.10 or newer THERE'S NO 32-bit (i386) BUILDS ANYMORE: https://dolphin-emu.org/blog/2014/05/19/obituary-32bit/ ARMv8/AArch64/arm64 packages now ;) Did you like this PPA? Bitcoin donation: 1MhU9RxaRhj3yd1c6fSQAQhDPxpwLY6WU5 Litecoin donation: LiGLDxjntT9GjX6S6fpbgBCN5akemyYQ7c More info: https://launchpad.net/~dolphin-emu/+archive/ubuntu/ppa Press [ENTER] to continue or Ctrl-c to cancel adding it. Hit:1 http://ppa.launchpad.net/deadsnakes/ppa/ubuntu focal InRelease Ign:2 http://ppa.launchpad.net/dolphin-emu/ppa/ubuntu focal InRelease Hit:3 http://packages.microsoft.com/repos/vscode stable InRelease Hit:4 http://ppa.launchpad.net/libretro/stable/ubuntu focal InRelease Hit:5 http://us.archive.ubuntu.com/ubuntu focal InRelease Hit:6 http://ppa.launchpad.net/system76/pop/ubuntu focal InRelease Hit:7 http://us.archive.ubuntu.com/ubuntu focal-security InRelease Hit:8 http://ppa.launchpad.net/ubuntu-toolchain-r/test/ubuntu focal InRelease Hit:9 http://apt.pop-os.org/proprietary focal InRelease Err:10 http://ppa.launchpad.net/dolphin-emu/ppa/ubuntu focal Release 404 Not Found [IP: 2001:67c:1560:8008::15 80] Hit:11 http://us.archive.ubuntu.com/ubuntu focal-updates InRelease Get:12 http://us.archive.ubuntu.com/ubuntu focal-backports InRelease [98.3 kB] Reading package lists... Done E: The repository 'http://ppa.launchpad.net/dolphin-emu/ppa/ubuntu focal Release' does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details. 

Thanks in advance for any suggestions.