Help a tired mama

My 15 week old sleeps great, through the night. She goes down and sleeps 9+ hours. She will even go down drowsy but awake and stay down till she falls asleep on her own without me sleep training.

BUT

She will not nap during the day unless she’s in my arms. The second I try and put her down she wakes up and starts screaming. It doesn’t matter where I put her, white noise or no, if I hold her for a while till she falls into a deep Sleep, it doesn’t matter. She will not go down. But if I leave her in my arms, she sleeps for 3+ hours. Help a mama out with any tips?