How to create a shared folder on windows with virtualbox + ubuntu, or set up a local network between them?

Question

virtual box

virtualbox with ubuntu 18.04 is installed on windows 10, during installation the minimal installation was selected, version virtalbox 5.1.20, created a shared folder, installed guest additions, added a user to the group, rebooted ubuntu, nothing helped, it just does not appear and everything. Next, I tried the option of creating a folder via samba, everything turned out fine, the network is detected, but 0x80070035 this error pops up and again I can’t get through to the files of another OS, the ithernet network is of course disabled because there is no cable, but how to make it I realized that I don’t know on one server, also in the virtualbox settings, the nat network is set to “adapter 1”, again, 2,3,4 can and should be connected, but they are not active

Answer 1

put the network in bridge mode.
then the network adapter of the virtual machine will transparently stick out to the same network as the host (I hope the computer is connected to lan).
in nat, for the services to work, you will have to forward ports, and this is usually either crap or simply impossible without picking the system (for samba, you will have to register ports because rpc allocates a port dynamically to it)
shared folders have always been mounted via fstab, a habit has always worked with a bang.
if you do automounting, make sure that there is a directory in the virtual machine in which you mount the shared.

Answer 2

https://losst.ru/kak-sdelat-obshhuyu-papku-v-virtualbox
well, guest OS additions must be installed