I have a Yun Rev 2 and was able to get it to work. Not sure I did it the correct or easiest way but hope it helps you.
Type in your Yun IP address on a web browser and type password to log in. Press the "configure" button.
Press the "advanced configuration panel (luci)".
Select "System" and then "software".
Press "Update Lists" (if first time after boot). Wait of few seconds for it to update.
Select "Available packages"
In the filter area type "samba" and press "Find package".
I picked "samba36-server" good bad or indifferent. Maybe it should have been client, luci-app-samba already appears to be loaded.
Install the package.
Can't remember if I did a reboot at this point but you should be able to go under "System" and then "Startup".
Make sure samba is in the list and is started.
Next select "System" and then "Mount Points".
Under Mount Points select "Add".
Now it gets a little tricky, you will need to do some custom settings. When all is said in done and you get back to where the mount point is added your mount point should look like;
Enabled checked, device name of your SD card, Mount Point /mnt/sda1, Filesystem vfat, Options umask=000, Root no, Check no.
Next select "Services" and then "Network Shares".
Click the "add". You should have the following in the row when done;
Name arduino, Path /mnt/sd/arduino, Allowed users blank, Read only not checked, Allow guest checked, rest is blank.
Don't remember if you have to reboot or not.
You should be able to get into Windows 10 and map it to a drive. It will be something like //192.168.0.15/arduino
Hope this helps, this use to be the old way on my Dragino Yun boards, it worked on the Yun Rev2 but with some extra unknowns. Maybe I didn't have to do any or some of the steps but it was just my routine to get things going with the older boards.