@lawlsh
Hello,
Here is a FAQ you can refer to know why the password is incorrect if you use the WPS to set up the range extender:
https://www.tp-link.com/en/support/faq/765/
In this case, we suggest you use another way to set up the range extender.
Please download "Tether app" on your cell phone from APP store/ Google play, and refer to this FAQ to install Range Extender on Tether app:
https://www.tp-link.com/support/faq/1373/
If you need any further help, please let us know which step you met trouble, what is the Error message, and send us a photo of LEDs on your range extender, thank you!
Have a nice day!