Powerbeats 3 Not Connecting with Samsung S9+. What to Do?

Sometimes the devices take a while to show up if there's too much 'noise' going on (other networks, more BT devices, etc.). Try hitting the Scan button a couple more times, and like Rukbat says, make sure the Beats are in pairing mode. I had no issue connecting mine to a pair recently, but I do believe it took a second scan to actually see the name.