How to test relay transaction using gsn staff on local evm environment?

I tried to test my gsn smart contract using Relay Provider from web3. I just followed this document but on my end this was not working well. https://docs.opengsn.org/javascript-client/tutorial.html#the-user-interface

var Web3 = require( 'web3')
const gsn = require('@opengsn/provider')
const ethers = require("ethers")
const conf = {
    ourContract: '0x10A51A94d096e746E1Aec1027A0F8deCEC43FF63',
    paymaster:   '0x3f84367c25dC11A7aBE4B9ef97AB78d5D5498bF5',
    gasPrice:  20000000000   // 20 Gwei
}

let gsnProvider = await new gsn.RelayProvider(window.ethereum, {
        forwarderAddress: conf.forwarder,
                paymasterAddress: conf.paymaster,
                verbose: false}).init()
    provider = new ethers.providers.Web3Provider(gsnProvider)
    userAddr = gsnProvider.origProvider.selectedAddress

Looking forward to hearing from talented engineers and developers.