Help for setting up samba on linksys wrt1900acs

Guy´s i need som help...
I am trying to acces a usb harddrive formatted as ext4, from a windows 10 pc connected on wifi.
I am able to see the drive in file explorer, but when i double click on the drive windows ask´s for user and password.
I haven´t specified any username or password. I followed the tutorials on the openwrt homepage.
Is there a default password and user? I haven´t configured any username or password so i am completely stocked.
I have searched and read a lot of topics but i haven´t ben able to figure this issue out.
I am a newbie in linux and samba.
any help would be much appreciated.

In luci/ui enable the Guests only option and if it still fails enable Force Root as well.