Insufficient light is causing stretch, likely soil is not in PH range for cannabis to uptake. For future reference, cannabis-friendly soil is buffered to a PH between 6.3 and 6.8. You can use a tomato-specific soil as well but have to worry about adulterated soils using harsh salts.
The medium should be damp but not wet, for the first two weeks a dome and misting inside of same will provide all the moisture the sprout needs until a taproot forms. Until then it derives all of it’s moisture out of the air.