Hi there and welcome
When you set the S4 uo for tethering you set a security key
If you forgot what this was then
Tap on Applications.
Go to Settings. Under the Connections tab, select More Networks.
Go to Tethering and portable hotspot.
Tap on Portable Wi-Fi hotspot.
Drag the slider to turn On Portable Wi-Fi hotspot.
There you will see the password ***** enter
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