BlueStacks is Android emulator which is basically running virtual machine with different operating system, therefore you can't access your files directly.
You can find your data files under
C:\ProgramData\BlueStacks\UserData\SharedFolder on Windows or
Library/BlueStacks/Android on Mac, but the data files are in VDI format (VirtualBox drive image).
So you can try to convert .vdi files into RAW image which you can mount by the following command:
VBoxManage clonehd --format RAW Root.vdi Root.img
Then you can try to mount these files by some software which can support Linux ext3 file systems.
Alternatively you can install Total Commander, Root or File Explorer (or similar app) in BlueStacks, then transfer your files into fake SSD card and they should appear in
C:\ProgramData\BlueStacks\UserData\SharedFolder folder. On Mac, you probably need to convert
SDCard.vdi file into RAW format (as mentioned above) and mount the image, or use VirtualBox software to access the VDI image.
Another easier way is simply to install FTP or SCP plugin for Total Commander app and transfer the files via network.