HTTP request for external API?

I tried to implement a payment API into my system but I have some doubts regarding the HTTP requests being called for the API and I wanted to clear the confusion.

As far as I know in general, GET request is used to retrieve data or information from a server while POST request is used to submit data to the server.

In my route calling the api, it will look something like:

Route::get('toyyibpay','ToyyibpayController@createBill')->name('toyyibpay-create');

Controller:

public function createBill(Request $request){
       
        $credit = ($request->amount)*100;
        $option = array(
            'userSecretKey'=>config('toyyibpay.key'),
            'categoryCode'=>config('toyyibpay.category'),
            'billName'=>'Fxxxx',
            'billDescription'=>'Top Up Credit',
            'billPriceSetting'=>1,
            'billPayorInfo'=>0,
            'billAmount'=>$credit,
            'billReturnUrl'=>route('toyyibpay-status'),
            'billCallbackUrl'=>route('toyyibpay-callback'),
            'billExternalReferenceNo' => '',
            'billTo'=>'',
            'billEmail'=>'',
            'billPhone'=>'',
            'billSplitPayment'=>0,
            'billSplitPaymentArgs'=>'',
            'billPaymentChannel'=>0,
            'billContentEmail'=>'Thank you for using our platform!',
            'billChargeToCustomer'=>2
          );  

    
          $url = 'https://dev.toyyibpay.com/index.php/api/createBill';
          
          $response = Http::asForm()->post($url,$option);
          
          $billCode = $response[0]['BillCode'];
          //dd($billCode);
         
         
          

          return redirect('https://dev.toyyibpay.com/'.$billCode);
    }

As shown in the method, I am passing data(parameters) to the server. As of now, everything works fine. My doubt is shouldn't a post request be used since this involves data submitting?