I wish ArchiveBox had such a feature where you can archive “private” and logged in pages. I often had the case where I then realized I only archived some login page.
To save logged in content, you can either pass it cookies.txt with the login cookies it needs, and it works pretty well. Alternatively, you can also use the SingleFile extension to snapshot what you want and upload it in place of the automated snapshot. This is also handy because the extension allows you to remove private data prior to screenshot, such as your name or username.
I personally have cookies in place for most common social media sites that need login (twitter, reddit), and if I need to snapshot something else occasionally, I do it manually and upload it to Linkding.
Also, it is possible to configure SingleFile extension to automatically push a snapshot to a REST Form API. You can even make it do so when you bookmarks something in your browser, to achive a flow where bookmarking something in the browser saves the page via SingleFile extension and gives it to ArchiveFile.
https://docs.archivebox.io/dev/Contents.html#api-reference
Also, look in the SingleFile extension options, under Destination.