It is the teacher responsible for teaching, not the sub. The sub will know what the teacher expects, because the teacher should leave a detailed outline of what is taking place during every lesson and in-between (snack time, lunch time, recess duty, etc.) The lesson plans left for you to follow must be easy to direct, and all of the materials you need for the lessons should be left in an obvious place.
As far as technology goes, I would never ask a sub to use a smartboard. I might , however, leave a short video for the class to watch, and I would make sure the sub knows exactly where to find the TV.
If you can't do something described in the lesson plans, it would never be considered your fault, but rather the fault of a teacher, who didn't leave clear instructions.
Best of luck,
~5th grade teacher