Virtualbox Guest Additions are the usual way to get Virtualbox Shared Folders to work. But GAs aren't officially supported in FreeBSD VMs. However, see this by forum volunteer 'MultiOS':
viewtopic.php?f=4&t=99606#p483279And a web-search on "freebsd guest additions Virtualbox" showed up this:
https://docs.freebsd.org/en/books/handb ... virtualboxAlternative idea: set up a Bridged or Host-Only network between host and VM, then make a real shared folder over the network. Virtualbox and Guest Additions aren't involved in this process. Web-search how to share a folder in one of the OS's and to access it in the other. See
Virtualbox Networks: In Pictures