If you need help finding where the episode is legally available in your country, let me know your region and I can point you to specific services.
You are looking for Episode 11, titled "Demons, Sunday School, and Prime Numbers." For a low-data or small-screen experience, the 480p version will be approximately 200MB. For the best viewing experience, consider official streaming services, but if you must download, ensure you scan files for malware and avoid "fake" download buttons on aggregator sites. young sheldon s01e11 480p