I had the same problem and was able to get it to work by doing the following:

Choose “Use an existing virtual hard disk file” and click on the folder icon to choose the file on desktop from downloaded OS X Sierra to install Mac OS on VirtualBox. Now click on the settings icon given at the top of the virtual box. You will be on the General tab. Click on System next to General. Folder Icons - Download 4844 Free Folder icons @ IconArchive. Search more than 600,000 icons for Web & Desktop here. The new version 4.5 of Folder Marker is almost ready! Soon AUGUST Before the release check the added ability to use JPG/PNG as folder icons. Hope you all enjoy the new Mac and mobile software updates. Customize your mac even more by using this simple technique to change your icons.

* Open the new folder icon in Preview

* Command-C to copy the image

* Get Info on the folder that you want to replace the icon

* Click on the blue folder in the top left (or PNG icon with apple logo from a failed attempt) - It should be outlined in blue

* Command-V to paste the new icon

Someone had a similar solution here:

Folder Icons Sierra Leone

Folder Icons Sierra Vista

But the key for me was opening the image in Preview and copying it. Drag and drop seems broken right now. Minitool partition wizard pro.

Folder Icons Sierra Download

Feb 6, 2018 8:01 AM