In your screenshot, mlrModel, fsrModel, etc. are the name of classes. They may look like structures but these things are absolutely not structures, they're objects, instances of classes. In order to get a mlrModel you would have to call whichever function creates such objects, possibly the class constructor, with the appropriate inputs. While matlab provides a way to convert objects to structures there is no reverse operation other than what is provided explicitly by whomever wrote these classes.
In conclusion, look at the documentation of whatever library you're using to find out how to create these objects. They're not structures.