Knitting pattern in the round
As I understand it, the instruction offers 2 different sizes:


Cast on 136 stitches if you want the pattern to repeat 4 times
Cast on 170 stitches if you want the pattern to repeat 5 times


The pattern itself has 34 stitches.
34 x 4 = 136
34 x 5 = 170

When the instruction says "cast-on and join, then work bottom border..." it means "Choose one of the given sizes and cast on the corresponding number of stitches, then join and work bottom border..."