How do I access folders created on Ubuntu with Windows?

I have an external hard drive on which I back up my files, and I've moved some files from an Ubuntu laptop to it as well. However, I can't find a way to open the folder containing these files with my main Windows 10 laptop. When I try to open the folder "VPC 3 : UBUNTU" (the "VPC" is just a name for the laptop with no special implications), the following happens:

It responds with "___ is unavailable. Make sure the disk is inserted..."

Solution 1:

: is an invalid character in Windows filenames.  Probably the simplest thing to do here is to go back to Ubuntu and rename that folder.