CordovaPayTM plugin called but does not redirect to paytm page

Here is my Code processFeeSubmission() hit function click event then paytm browser is not open in device. and i am following https://github.com/latamind/cordova-plugin-paytm
for paytm integration please help me why am I unable to open paytm in the browser ?

           declare var window;            
          export class WardFeeDetailPage extends BasePageComponent {
          paymentReceipts: Array<PaymentReceipt> = [];
          user: any;
          feeDetail: FeeDetail;
          currentDate: Date = new Date();
          totalAmount: number = 0;
          message2: Message;

        processFeeSubmission({ selectedOption, feeDetail }) {
  window.cordova.paytm.startPayment(paytm.merchantId, this.user.username, paytm.channelId, paytm.industryTypeId, paytm.website, orderId, paytm.email, this.user.contactNo, this.feeDetail.balance, callbackUrl, checksum, paytm.isProduction || false, (res) => this.onPaytmSuccess(res), (e) => this.onPaytmError(e));

} }

from CordovaPayTM plugin called but does not redirect to paytm page