Indoor aralia has brown spots - excessive watering is usually to blame. Spider mites or too much water are usually the cause.
Brown leaves indicate excessive watering. Brown edges also indicate overwatering. Yellow leaves, on the other hand, indicate too much light or sun. Direct sunlight is not natural for the plant due to its origin in Asia. Even if the indoor aralia reaches heights of up to six meters in nature - don't worry, in Germany the houseplants rarely grow over one and a half meters high.