Jurism is available at juris-m.github.io/release
Zotero is available at www.zotero.org/download
Plugins that work for both are available at www.zotero.org/support/plugins
Login in to your zotero.org account here: www.zotero.org/user/login
Jurism/zotero are tools that help you collect, organize, cite, save, and communicate your research, both individually and collaborating in groups. For the differences between jurism and zotero, see this article on it. Where I refer to jurism/zotero below, I mean that you can use whichever of these two you have installed; their behavior is identical.
You need to backup your jurism/zotero data regularly. Syncing with the zotero server is not the same as backing up, and should not be relied on. If you delete something accidentally and then your jurism/zotero automatically syncs with the server, the data will be gone. To avoid this, follow these directions and backup regularly.
Regular zotero is a general purpose scholarly open-source citation and research manager. It is optimized for broad appeal and usefulness in all areas of scholarly research. It works on Windows, Mac, and Linux operating systems, has plugins for Microsoft Word, LibreOffice, and OpenOffice word processors, and works with Google Docs, email, and many other applications. You have a choice of using it with Firefox, Chrome (& Chrome-based browsers like MS Edge or Vivaldi), or Safari.