In ODK data with volume 500+ uploaded to odk server can not be retrieved back unless you pay ODK. That is my data i captured in my research, hence i am the owner, My opinion is better to sell the software or training services and leave freedom of data usage to users of the app. Moreover could allow the users to configure their own servers. Most organisations do not like their data to be controlled by other organisation.
Thanks and you are welcome.
I'm not sure what ODK server you are using, but ODK Aggregate, the stock ODK server, is free and lets you install on a local server or on Google App Engine. Regardless of your provider, the ODK team does not have any control over or access to the server.
If you choose to go with Google App Engine or some cloud provider (e.g., Amazon Web Services) you may have to stay within a quota that resets every 24 hours or pay those providers some nominal fee. None of that money comes to ODK.
To be clear, ODK Aggregate is designed to solve the issues you raised. It gives you total control over the data and where the data lives. And for the vast majority of users, it's free to host.