I'm running an Ubuntu 20.04 guest on a Windows host using Oracle VirtualBox and Vagrant.

I'm trying to update my Guest Additions which is currently at 6.1.5 to match the VM at 7.1.4.

First, before booting the VM, I went to Storage and left it on empty. But then when I click on Devices inside the VM, and click on Insert Guest Additions CD image, I get this error:

Could not mount the media/drive C:\Program Files\Oracle\VirtualBox\VBoxGuestAdditions.iso (VERR_PDM_MEDIA_LOCKED).

I've read all the guides. None works for me. Please, help me set up my guest additions.