Jessica,
Welcome to BP! I'm not sure about the laws in Iowa, but there is a similar requirement in Texas, so I'll tell you how it works here.
Once you get your RE license in Texas, you are not allowed to work independently as a salesperson, but must choose a RE broker to "hang your license" with. I believe the intent of these types of laws is to keep new real estate licensees from jumping right in and working with the public independently when in reality you really still do not know what you are doing!! ;-) The intent is to have you work with someone who has been in the business longer who can help teach you the ropes and, in theory, keep you out of trouble....especially since real estate does involve quite a bit of money, working with the public, & legal issues.
In Texas, your license is not considered "active" unless you have a broker. And you can't work independently until/unless you have worked 4 years as an active agent (with a broker) and after 4 years you study and get your own broker's license.
What this probably means is that you'll have to find a broker to hang your license with so you can remain "active", but who understands that you will not be acting as a truely active salesperson (translate: you won't really be making him/her any money to speak of). Some brokers are okay with this. You just have to find one that is...and you should find one that also likes working with investors.
There might be another option. If all you are looking for is MLS access, you might try finding an agent or broker to "help" with CMAs. In Texas, agents are allowed to have "assistants" that we can set up with MLS access for additional fees. If Iowa is set up the same way, you might be able to locate and befriend an agent who would let you have access if you offer to pay the fees, offer to give her/him any non-motivated seller leads you get, offer to help with their CMAs, and/or buy/sell your properties thru him/her, etc. (Again, as long as this is allowed/std practice in Iowa.)
Hope this helps!
-Linda