Linux – Share .iso files on CentOS for remote mounting anywhere via Internet

Assuming you're following these instructions (without success), here are options that don't involve a flash drive:

1. Attach a USB CD/DVD drive.
2. Open up the case, temporarily attach a regular SATA CD/DVD drive for installation.
3. Set the local DHCP server to enable PXE booting, install Ubuntu over the network.

I think you have multiple things going on here.

You'll never be able to boot a non-x86/x64 operating system in VMware Workstation. It isn't a CPU emulation environment, but rather a virtualization environment for the host CPU.

That having been said, it sounds like you've taken an image of a partition and turned that into a disk image. The VMWare Workstation BIOS is looking for a partition table on this disk and isn't finding it, so it's not even going to attempt to boot it.

You're able to mount the file loopback in a Linux installation because it does contain a valid filesystem image, but it lacks the necessary partition table to make it bootable to an x86 BIOS.

You could put together the necessary partition table to make the VMware Workstation BIOS attempt to boot the disk, but even if you do it's still not going to be bootable on an x86 machine.