Boot camp assistant gives "Windows support software could not be saved to selected drive" Error Installing Win 10 on MBP2015 I'm new to mac and trying to install Windows 10 on my Macbook Pro with specs

Macbook Pro Retina Mid 2015
Using macOS Sierra 10.12.6

I'm tying to install Windows 10 with BCA. But all the time I get this error at the end.

“Windows support software could not be saved to selected drive. An error occurred while saving the Windows support Software”.

My Macbook saves the Windows support software and windows ISO somewhere inside the mac-OS system so I don't need flash drive. And BCA don't give me the flash drive and download support software options. It asks for Windows ISO and then partition the drive and then goes straight for the downloading of Window Support Software.

Another problem is each time I get this error, BCA downloads all the Windows Support Software again. Which takes time and data (I'm using WiFi-connection speed 350kb/s).

I have also tried manually installing Windows 10 But that gives me this error while selecting the target window partition that I have created using Disk Utility.





The output from the command diskutil list is given below.

/dev/disk0 (internal, physical):
   #:                    TYPE NAME              SIZE       IDENTIFIER
   0:   GUID_partition_scheme                  *500.3 GB   disk0
   1:                     EFI EFI               209.7 MB   disk0s1
   2:               Apple_HFS Macintosh HD      499.4 GB   disk0s2
   3:              Apple_Boot                   650.0 MB   disk0s4 


So, anyone please help me to solve this. I've spent last week searching on internet but nothing works.

Thanks
I will address your attempt to manually install Windows 10 without the use of the Boot Camp Assistant. Here are some points.


You are using Sierra. This is good in the sense that High Sierra has introduced APFS. This has caused some problems that you will be avoiding.
You created a bootable USB installer. I do not know how you did this, but you do have to copy the Windows Support software to this USB flash drive before installing Windows. If you can not do this, let me know.
I appears you created a FAT formatted fourth partition labelled "BOOTCAMP". I do not know what procedure you used do accomplish this. However, a FAT format for this partition caused the Windows installer to incorrectly believe you have a MBR partitioning scheme. You should have formatted this partition as "Mac OS Extend (Journaled)".
When the Windows installer asks "Where to install Windows?", you should proceed as follows. First, delete the fourth partition. Next, select the free space. Finally, select "Next" to continue.