What are the functions setPublicChainlinkToken & setChainlinkToken in Chainlink API call?

I was following the tutorial of Chainlink docs at https://docs.chain.link/docs/advanced-tutorial/ to make an API call from my smart contract. However, I am still not able to understand the function setPublicChainlinkToken() that is being called in the constructor of APIConsumer. I am trying to fetch the temperature of a city through the API call. But my contract gives an error in compilation saying:

APIConsumer hit a require or revert statement somewhere in its constructor

The above error is very generic and I am unable to understand what is the issue. Below is my contract code and the script which I am using to deploy it.

What params do I need to pass in the deploy script?

APIConsumer contract

// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;

import "@chainlink/contracts/src/v0.6/ChainlinkClient.sol";

/**
 * THIS IS AN EXAMPLE CONTRACT WHICH USES HARDCODED VALUES FOR CLARITY.
 * PLEASE DO NOT USE THIS CODE IN PRODUCTION.
 */
contract APIConsumer is ChainlinkClient {
    using Chainlink for Chainlink.Request;
  
    uint256 public temperature;
    
    address private oracle;
    bytes32 private jobId;
    uint256 private fee;
    
    constructor () public {
        setPublicChainlinkToken(); // Do I need to pass any params for this?
        // if (_link == address(0)) {
        //     setPublicChainlinkToken();
        // } else {
        //     setChainlinkToken(_link);
        // }
        // setPublicChainlinkToken();
        oracle = <oracle id>; // Removed oracle id and jobid values for post
        jobId = <job id>;
        fee = 0.1 * 10 ** 18; // 0.1 LINK (Varies by network and job)
    }
    
    /**
     * Create a Chainlink request to retrieve API response, find the target
     * data, then multiply by 1000000000000000000 (to remove decimal places from data).
     */
    function requestVolumeData() public returns (bytes32 requestId) 
    {
        Chainlink.Request memory request = buildChainlinkRequest(jobId, address(this), this.fulfill.selector);
        
        // Set the URL to perform the GET request on
        // "https://min-api.cryptocompare.com/data/pricemultifull?fsyms=ETH&tsyms=USD"
        
        request.add("get", "http://api.weatherstack.com/current?access_key=7940b0c1136901badcb304724132b234&query=Mumbai");
        
        // Set the path to find the desired data in the API response, where the response format is:
        // {"RAW":
        //   {"ETH":
        //    {"USD":
        //     {
        //      "VOLUME24HOUR": xxx.xxx,
        //     }
        //    }
        //   }
        //  }
        request.add("path", "current.temperature");
        
        // Multiply the result by 1000000000000000000 to remove decimals
        // int timesAmount = 10**18;
        // request.addInt("times", timesAmount);
        
        // Sends the request
        return sendChainlinkRequestTo(oracle, request, fee);
    }
    
    /**
     * Receive the response in the form of uint256
     */ 
    function fulfill(bytes32 _requestId, uint256 _temperature) public recordChainlinkFulfillment(_requestId)
    {
        temperature = _temperature;
    }

    // function withdrawLink() external {} - Implement a withdraw function to avoid locking your LINK in the contract
}

Javascript Script To Deploy:

const APIConsumer = artifacts.require("APIConsumer");
module.exports = async (deployer, network, [defaultAccount]) => {
  try {
    await deployer.deploy(APIConsumer);
  } catch (err) {
    console.error(err);
  }
};