Linux Magazine PDF downloader for subscribers
You can install it by typing: snap install lmdownload
Afterwards you should be able to run QOwnNotes with the command lmdownload.
Snaps are working on many Linux distributions like Ubuntu, Arch Linux, Debian, Fedora, openSUSE, Gentoo Linux, OpenWRT, open embedded and yocto project.
Please note that you are only able to download PDF files to your home-directory if you are installing the snap (unless you are breaking out of the confinement by running /snap/lmdownload/current/lmdownload directly).