Folding only adds numbers together, so the total never changes. Both strips add up to 31. Your largest target number, 19, must be a stack of several cells added together.
Hint 2: the length budget
The strip has 9 cells and the target has 3, so the folds together must remove 6 cells. A fold removes as many cells as its shorter side has.
Hint 3: the first fold
The first fold goes between cell 8 and cell 9, counting cells from the left.
Full solution
Show every fold
Fold 1 of 3
124527622→12452764
Fold between cell 8 and cell 9. The right side flips over the left side.
Fold 2 of 3
12452764→128119
Fold between cell 5 and cell 6. The right side flips over the left side.
Fold 3 of 3
128119→11119
Fold between cell 3 and cell 4. The right side flips over the left side.