Underarm:
I needed twice the number of rows indicated to mesh with pattern width dimensions (16 rows for sm, 20 med, 24 lg).

Drape:

Something seemed off on row 15 of drape but not sure. Here’s my take:

Row 14: omit last ch st
Row 15: * (Ch 4, sc into next ch space) repeat 7 more times. (Ch 2 dc2tog into next ch 1 space) repeat 4 more times. Ch 2 (dc2tog, ch 3, dc2tog) into ch 2 space. (Ch 2, dc2tog into next ch 1 space) repeat 4 more times. Ch 2, sc into next ch 1 space. * Repeat from * to * (4, 5, 6) more times. (Ch 4, sc into next ch space) repeat 5 more times.