Hi @Munaib Ishaq ,
That's right. If you haven't Active Directory Domain Services installed to your environment, you need to use server's local account for giving permissions.
You can create user accounts for those users.
To access Local users and groups: Click Start > Run. Enter lusrmgr. msc in the box and click OK.
A certain user can access this network share by a local account SERVER\Account.
If you want an external users to access resources, you need to make changes to firewall too.