How to build an iPhone app for distribution on the clients account?
See the answer to this question. Looks very similar - you don't have to provide source code, but they do need a Mac (or otherwise provide the distribution certs) to resign the binaries.
iPhone ad hoc distribution with team agents certificate
Since I never got any response to this question, I'll answer it myself.
Or rather, I'll refer to the answer rob5408 provided to this question:
iPhone: Can a dev other than team agent build an app for distribution
That did the trick.
Team Agents the only ones that can build Ad Hoc?
When you generate a signing request in Keychain Utility (the first step of generating an Ad Hoc profile), it simultaneous generates a private key and saves it to your keychain. You can only build against the Ad Hoc provisioning profile if you have that private key in the Keychain on your Mac.
So your solutions are
Get them to export their private key from the keychain and send it to you. You then import it into your keychain. They should also send you the Ad Hoc mobileprovisioning file they created. You drag and drop this onto xcode.
Generate the signing request on your machine, and send it to them to generate a new Ad Hoc profile which will then only work on your Mac (though again, you could send them the private key).
The final option would be to send the source code to them to compile the Ad Hoc builds.
iPhone ad hoc distribution in a team environment
You are expected to use separate development and distribution certificates; you actually set up different configurations for them. The "nightmare" comes when you use several different development certificates. If anyone touches the certificate setting on the Debug configuration, it must thereafter be set manually (which is a pain in the ass, of course).
So no, there's no problem with the Team Agent giving you his distribution certificate and private key (you'll need both). He needs to realize that Apple will hold him responsible for your distribution of packages, though.
iPhone ad hoc distribution as a team admin with team agent's certificate?
What you are missing is the key pair that was used to create the development certificate. I've been through this exact scenario and what you need is for your team agent to export his/her private key to send it to you so that you can install it in keychain on your machine.
To do so they would need to start up Keychain Access.app, browse the certificates section of the app then they can right click on the private key and export it for you. They can set a password on the exported private key so that it can only be installed by people that have the password.
Once that is done they send you the key and you install it into keychain on your development machine. You will then be able to use the certificate(s) they generate with that key.
Build an app for iPhone no apple developer account
You can build a native iOS app on physical iPhone device without having a paid developer account. In the past it was not possible but Apple changed that few years ago. Currently it is enough to have a free Apple ID account to build an app from Xcode to your physical iPhone device. Note that you still need to have a Mac to create native apps. Check this: