Windows expects to see a user account from it's own domain. Without specifying a username/password in the mount command, there's no credentials for windows to use to allow access to the share.

"Everyone" in the context of a Windows share is every user account in it's domain (which is the local user database on a Windows machine not on a domain).

https://unix.stackexchange.com/questions/436178/how-to-use-a-credential-file-when-mounting-a-samba-share-using-mount-command

It's using the current user "root" as a login user for the share. You can specify a different share user using following command:

mkdir /mnt/cifs
mount -t cifs //server-name/share-name /mnt/cifs -o username=shareuser,password=sharepassword,domain=nixcraft
mount -t cifs //192.168.101.100/sales /mnt/cifs -o username=shareuser,password=sharepassword,domain=nixcraft

Try specifying a user that does exist on your Windows machine. Not quite sure if it will work without a password, but you can try.

https://www.cyberciti.biz/faq/linux-mount-cifs-windows-share/

I'd just create a generic file share username and password locally in windows and use that from linux. It's better to have some sort of credentials for your share anyway

Don't use root@

Btw if there is no password for the smb share, then leave all password attempts blank.

You can follow the other recommendation about mounting SMB shares under Linux or eventually setup an SSH server on Windows and use SSHFS to mount it on the Linux machine.

SSH is usually faster than SMB however both of them will have issues, what if the network goes down the windows machine sleeps, reboots, crashes or someone steps on a network cable etc? You are better by avoiding those kinds of setups all together. It is very likely that the connection will drop and the Linux machine will have trouble writing on the mount causing errors and screwing the files. Those setups won't also translate unix permissions and other details very well and might create other issues for you.