Help? SD Card doesnt work

Device: Chrome OS
Problem: not working sd card custom installation

  • Logs:

username@penguin:~$ flatpak --installation=extra remote-add flathub https://flathub.org/repo/flathub.flatpakrepo
error: Flatpak system operation ConfigureRemote not allowed for user
username@penguin:~$ flatpak --installation=extra remote-add flathub https://flathub.org/repo/flathub.flatpakrepo
error: Remote flathub already exists
username@penguin:~$ flatpak --installation=extra install flathub org.DolphinEmu.dolphin-emu
Looking for matches…
error: Unable to load summary from remote flathub: Signature made Mon 01 Jan 2024 03:20:53 PM CET using RSA key ID (id)
Can’t check signature: public key not found

Edit:

  • Custom installation:

[Installation “extra”]
Path=/mnt/chromeos/removable/SD Card/flatpak/flatpak
DisplayName=SD Installation
StorageType=harddisk

I think you need to add more context