Ew. No contract may be an issue as you've no access to updates at all without one. People use to exploit the Cisco download site by buying a support contract for the cheapest possible device and then using the access granted by that to download everything they needed but Cisco finally implemented contract specific download restrictions at the start of the year.

Cisco being Cisco, you don't get everything just by buying the box. IOS is licensed based on features and you need to get a license which means $$$. The old system was that each IOS version had an associated feature set file and you just downloaded the feature set that you needed. The new system for ISR G2 routers like this 2921 is that you just download a massive universal image and unlock the various feature sets by typing in a device specific code.

Buy a license for say the Security feature set. Cisco will give you a Product Activation Key. You go to cisco.com via web browser or directly on the router if you've already got internet connectivity and type in the PAK, SN# and PID of the device. That'll give you a Software Activation license which needs to be installed to actually turn on that feature set.

I assume that you'd want at least the Security feature set so you should check into what was actually ordered for this router before you trek over there.

The version of IOS you'll want is 15.0M and nothing with a T in it. M = Mainline aka the "stable" branch. T = Technology and its where new features get added along with new hardware support so its sometimes a bit flakey with unusual bugs.

Are they Cisco APs?