Finished size: 38” wide x 52” long

I changed up the pattern a bit and did 6 rows for the 3 middle stripes instead of 4 as called for in the pattern.

5/3/24:
With A, ch141, R1-12 (12)

5/4/24:
With B, R13-18 (6)
With A, R19-30 (12)
With B, R31-36 (6)
With A, R37-40 (4)

5/5/24:
With A, R41-42 (2)
With B, R43-48 (6)
With A, R49-60 (12)
With B, R62-66 (6)

5/6/24:
With A, R67-78 (12)

Border:
R1: Sc around as per pattern.
R2: Shell st in corners (7dc),
On short sides, I did shell (6dc), skip1 st, sc in next st, skip 1 st across
On long sides, I did shell, skip 2 sts, sc in next st, skip 1 st across