To be able to access a shared folder or copy paste in the guest OS in VirtualBox, one need to install and enable guest additions in VirtualBox guest OS first.
I am on Manjaro OS, but it should not matter what OS you are on. The end result of this article is to run macOS in Virtualbox on any Linux OS.
I was working on a web project and needed to share the VirtualBox appliance(OVA file) with others to test it out(hosting and Internet is not an option, an offline solution). To accomplish this without the user configure anything, I created host only network on VirtualBox before sharing. That way they can just import the appliance and run it. To access the web app through an IP, we will create a host only network for it.