The link to the fedora forum was added in my last post.
You didn't answer how you have installed zotero. If it isn't installed as flatpak you wouldn't find the file there.
If you have installed zotero as flatpak (you can check this in the software manager at installed)
you should find it at the places mentioned in the fedora forum.
To show the hidden files press ctrl+h after you have opened your file manager. You need them when you want to search for the zotero flatpak at
/home/USERNAME/.local/share/flatpak
(replace USERNAME with your username )
The other place where it can be stored is at
/var/lib/flatpak/
The easier way is probably to use the zotero-deb if you are not familar with tarballs. Then you don't need to search for the flatpak file. But if you want to use another installation method you should remove the flatpak/snap/tarball first.
To install zotero:
wget -qO- https://raw.githubusercontent.com/retorquere/zotero-deb/master/install.sh | sudo bash
sudo apt update
sudo apt install zotero
For the zotero libreoffice plugin you also need a java runtime environment. Maybe these steps mentioned here can help you?