When you provide services for multiple companies and need to restrict access based on organization, you can create "Accounts" that users are associated with. If Dan, Mary, and Ken work at Company A, simply create a "Company A" account, and create user logins for the three employees in the "Company A" account. You can even assign permissions to them individually if required.
Create user logins for employees to access media, upload pictures, post blogs, and more. Limit access to only the features you want them to use.