It’s important to make sure your folding shower bench is big enough to be comfortable, but not too wide for your shower. It should fit on the wall across from the shower head. You’ll want to make sure the inner side of the shower bench maximum 1.5” from the wall, to be ADA compliant.
You’ll also want to make sure the outer edge of the folding shower bench doesn’t stick out over the shower threshold to prevent the seat from pushing the shower curtain out over the low threshold, causing water to run out onto the bathroom floor.