An Apple ID is associated with an iTunes account. It is required to download and install updates as well as upgrades to the Server/OS X software. The account requires a credit card except to obtain free software in iTunes. However, updates and upgrades for system software are done through the App Store which gets your account via the Apple ID you setup in iTunes.
But Apple has provisions for corparate users, so I suggest you contact them to see about what is needed to establish a corporate account. They probably don't require a credit card and can be done by PO or corporate credit card or direct billing.
Apple Store Customer Service at 1-800-676-2775 or visit online Help for more information.
To contact product and tech support: Apple - Support - Contact Apple Support.
For Mac App Store: Apple - Support - Mac App Store.
For iTunes: Apple - Support - iTunes.