Same problem on 2016 Siesta Sprinter 24ST I used Trim-Lok drip rail, Has 3M adhesive strip on the back. Installed in 2016 still there with no problems. Channels all the water away from the door.
Began at roof seam forward of the AC. and exit aft of the awning. Used a gutter extension there. RV dealer had it by the foot. Also on Amazon. Vinyl paint to match..
U.S. Coast Guard retired- 1956-1985
Lily- the Pug
1972 Moto Guzzi Eldorado