All products by i-net /// software store their data in a file persistence by default. That is, by default, a directory located on the server machine the product is installed on. Another option is a cloud persistence, such as a MongoDB.
That means that your data is always stored on your side. Our products only perform limited requests to our company servers, specifically license validation and update checks. Even in that case: our products are build to work without any internet connection at all.
Sensitive data is additionally encrypted, so even with access to your data storage locations, one can not simply open PDF files or CoWork conversations.