To care for a Begonia maculata, provide bright, indirect light, and water when the top inch of soil is dry to keep the soil consistently moist but not waterlogged. Maintain high humidity (around 50% or higher) and a consistent temperature between 65–75°F (18–24°C), while fertilizing every two to three weeks with a half-strength balanced liquid fertilizer during the growing season. 
Light
Place in a spot with bright, indirect light. Direct sun can scorch the leaves, while too little light will cause the polka dots to fade. 
Watering
Water when the top inch of soil feels dry to the touch.
Keep the soil consistently moist but not soggy to prevent root rot.
Avoid letting the plant sit in water.
Use room-temperature water to prevent shocking the roots. 
Humidity and temperature
This plant thrives in high humidity (around 50% or higher). Consider using a humidifier or a pebble tray, especially in dry winter months. 
Keep temperatures between 65–75°F (18–24°C). 
Protect the plant from cold drafts.