Kathmandu website has awesome information -https://www.kathmandu.co.nz/blog/how-to-wash-a-down-jacket.

Machine Washing - Wash your down jacket on a gentle cycle at 30 degrees °C. If it's available, select the ‘extra rinse’ option

NOTE: Skip the spin cycle. It’s better for your down jacket to drip dry and/or use a tumble dryer. 

Hand Washing - Soak your down jacket for up to 60 minutes in a sink. Rinse by lightly squeezing out excess water (don’t wring it!) and follow the drying steps below. 

Drying - Lay flat to dry on a clothing rack. Don't worry if it looks crumpled or feels heavy, it will fluff up as it dries.

NOTE: It’ll take around 24–48 hours to drip dry depending on the weather conditions. As it dries, keep giving it the occasional fluff, particularly around any wet clumps of down.