Based on the information in your question there could be a number of things happening and, unfortunately, your Manage my Home profile was not completed to provide any additional information.
This model uses an electric clutch, which means the belt does not loosen or slip when the blades are not turning. An electric system actually stops the entire belt drive from spinning instead. On this type system, the belt is always at the same tension and should always be tight enough not to slip on any of the pulleys.
These electric clutch systems require a strong battery and properly operating charging system or they could stall your engine. Also, there are a number of electric systems designed to stop the engine if the mower blades are engaged when it may be unsafe, such as if you get out of the seat. Any short or switch issue with these safety circuits can cause the engine to quit when you try to start the blades.
This is an older model, so it possible you have some wear or drag issues with the deck itself, but with an electric clutch these issues will usually cause belt slipping or belt damage rather than stalling the engine. It would be better, and probably cheaper, to start with checking the electrical systems.
Be sure to update your Manage my Home profile and you can view manuals for your products online to see more detailed information on the deck and electrical systems.