I may be wrong, but remote client verification is required by design in Windows Networking - and since Samba is little more than a reverse-engineered Windows Networking, it’s perfectly possible that password prompts actually can’t be disabled. Just my two € cents…
If I’m not mistaking you can do this by going to (on the server)
Yast Control Center > Network Services > Samba Server
Select the share
Edit > Add
Search in the list for the option Guest OK hit the OK button and set the value to Yes. Restart Samba and it should work.
In the Global section of /etc/smb.conf add the parameter “security = share”.
Your smb.conf needs to be edited as root. See “man smb.conf” for the use of
this parameter. I will confess it has been many years since I’ve used this
setting. I seem to remember that Windows would ask for a username/password
but let you in no matter what you supplied, but I may be wrong here.