Impossible to configure Keepass XC?

I'm using the flatpak version of LibreWolf, but I have no idea how to configure the Keepass XC Password Manager. I got the addon from the Firefox addons page, but it won't sync with my Keepass XC database.

I'm pretty sure it's because it's configured to use the "Firefox" data directory, and not LibreWolf, but I don't know where LibreWolf's data directory is. It isn't in the user directory like Firefox, even though the profile creator appears to indicate it is.

Also, this is a bug for Keepass XC, but once I browse for a custom directory, a file browser window pops up, and you can't do anything in it. It's basically frozen and cannot be closed without using the terminal/system monitor.