I don't think you can do much with the dynamic disk as it is affecting the disk (not a partition). A few options you can do (depends on your condition):
- Redo the HDD into Basic Disk - not recommended as it will need a full wipe, and you can't extend the partition into a single 6TB
- Have the Linux as a Virtual Machine (using VirtualBox or similar things) - Pro: You keep everything intact, and have Linux on top. Cons: Both Windows and Linux are sharing resources.
- Add another HDD and install Linux there
- Run linux on an external HDD (it is possible, and via USB3.0 the speed is decent. on USB2.0 its pretty bad speed)
Depends on why you wanted Linux, having Linux as VM, or external HDD/USB Stick is probably best option for now without doing any damage to your existing installation.
Also someone else has answered something very similar: How to install Linux on a dynamic disk without losing the disk configuration?
Hope this helps.