Install fails at the end. v6.12 on Max OSX 10.14.6

[pbesong]

I had VB before and trying to install on a different laptop but every time at the end of the install it fails with

The installer encountered an error that caused the installation to fail. Contact the software manufacturer for assistance.

I don't know what to try next.

[pbesong]

I got it to run, but I get the message "no bootable medium found". I cannot find anything related to Windows 7, which I want it to run. I only had the VB install and extension pack. Where do I locate Windows 7 for it to run? I went to Settings > Storage > Empty and selected the disk icon next to SATA Port 1 but I don't know where the file is that I should specify here.

[mpack]

I got it to run, but I get the message "no bootable medium found". I cannot find anything related to Windows 7, which I want it to run.

I hope you weren't expecting that a free VirtualBox download would bundle free Windows licenses! So yes, "No bootable medium found" is to be expected until you insert a bootable setup DVD (or ISO image of same).

VirtualBox is a PC hardware simulator. Your situation is no different than if you had bought or made a blank PC. Normally such a PC is discounted because it doesn't bundle an OS license. In the VirtualBox case the discount is 100%! Long story short: you have to obtain then install an OS. See chapter 1 of the user manual for general instructions.

Where do I locate Windows 7 for it to run?

If you don't already own an unused Windows 7 license and install media then you need to buy it, e.g. second hand from eBay. Be careful about buying branded licenses, e.g. from Dell or HP, and make sure it's a proper setup DVD, not a rescue DVD.