How do you see a saved Wi-Fi password on Android without root privileges

Since you cannot see the contents of data folder without rooting the device, I'd suggest you to pull the wpa_supplicant.conf file using adb.
You'll need a Laptop/PC for this method.

Here's how to do it.

• In settings, open About phone.
• Click on Build number 5-6 times until you get the "You're now a developer" toast message.

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• Now go to developer options in settings and switch Android/USB debugging to on.

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• ​If you have an option of Root Access, set it to ADB only.

• Now, open your Windows desktop and download and install adb drivers. (You can download the driver's from adbdriver.com)
• Download and install platform tools (minimal adb and fastboot) fromhttp://forum.xda-developers.com/...
• Open the folder where you've installed the above tools. Hold the Shift key and right click inside the folder to click on Open Command Window here.

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• To test whether ADB is working properly, connect your Android device to your computer using a USB cable and run the following command: adb devices

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You should see a device in this list.

• Now that we've successfully connected the device in ADB mode, run the following command to pull the file from your phone: adb pull /data/misc/wifi/wpa_supplicant.conf c:/wpa_supplicant.conf
• This will fetch the file from your phone and copy it to your C:/ drive.
• Open this file in notepad and Voilà!