Plex PPA has a wrong PGP key

Hello,

when I’m trying to add the plex repository to my list i get the message, that the PGP key is wrong for that repository.

I get the error message after running

$ sudo apt-get update

Due to security reasons Ubuntu blocks the repository and doesn’t allow me to install plex via the repository.

I’m using this: https://support.plex.tv/articles/235974187-enable-repository-updating-for-supported-linux-server-distributions/