If you fail, try installing the Linksys extender setup by hitting the WPS button, Don't panic; simply follow these instructions. You won't need a WPS button. 

First, insert the Linksys RE6500 extender power plug into the outlet. Go to the WiFi settings on your computer by taking it now. Join the laptop or computer to the Linksys extender's default network after that. Launch the browser after that, and then type extender.linksys.com into the address box. Please enter the information requested on that page. Select the WiFi network you want to expand after clicking the setup wizard option. After entering your information, select the connect option. The Linksys RE6500 extender unit has now been successfully set up with the router. The Linksys web portal has now finished the Linksys RE6500 setup process when using the separate method steps.