I got interested in VA work because of my running/playing TTRPGs (namely horror ones), so I understand kinda where you're coming from. Good Job : )

Remember with slates, they aren’t really necessary and can add more audio to the audition that isn’t needed which can sometimes cause some directors to ignore them. For homework, it’s ok but for real auditions I would avoid doing this. You want to make sure you are projecting your voice so that you are fitting the scenario of being in a gym with no mic so that its believable to the audience. Articulate your words so that they can understand each word clearly and to keep the flow and clarity of the performance nice and strong. Take bigger breaths and work on your exercises and reading aloud. Over time, this will all get a lot easier as long as you practice, practice, practice. Good job!