The Nice Memberships does not support an enrollment feature that will allow companies to register a set number of employees. Basically, the extension is designed to set up one user account per subscriptions. If you are able to find a different third party extension that will allow a user (USER A) to register other users in to your Joomla account then, you can use Nice Memberships to sell the initial registration/enrollment to User A. If you find such an extension, please report your findings here. I am looking for this kind of extension for a background project that I am working on.
Also, the extention requires you to have the Joomla's core account registration, which I stupidly didn't install on the install of the site - any idea where I can download this from (the Joomla one, nothing special).
I didn't know there was an option to not install Joomla's user manager and registration. I was under the impression that its installation was mandatory. If you have simply turned off the site's registration, you can turn it back on again in the User Manager's options.
~ Best regards