a multi tenant (SaaS) accounting and reporting application

we need the application to be multi-tenant as we are selling this application to multi customers, where an employee in a company somewhere in india can access the relevant information to their business only and his administrator gave him the permission to read only . whereas another business in saudi arabia can only access their relevant data that their users can access. this can be achieved technically by either using (tenant id) as a main key in the database or either use multi schemas .(noting that its gonna be a shared database ) . so the application will include : - control panel to add the new users where we can only access - a login page for the customers to view the application and show their relevant data - shared database . See attached to understand the core cycle of the application and the database for the application Further details will be explained later