Flatpak Linux installation issue

I had previously had citra up and running on my linux system

After upgrading I had to reinstall citra via flatpak

It wouldn’t install but it gave me the the following flatpak error

error: Unable to load summary from remote citra-nightly1-origin: GPG signatures found, but none are in trusted keyring

I tried purging flatpak and reinstalling but with no difference.

How can I correct this?

Thanks

Using LMDE 4 (linux mint debian edition)

In order for us to provide better support, we need to see the log generated by Citra. This guide will walk you through how you can obtain the log file: How to Upload the Log File.

I used the following installation commands

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

and then

flatpak install https://flatpak.citra-emu.org/citra-nightly.flatpakref

Thanks.

I managed to build citra from the source so its ok.
But there still seems to be problems with installing via flatpak.
thanks