Getting a "KeyError" in my currency converter

I'm trying to make a currency converter and I'm getting this error, what's the reason?

I'm using alphavantage to get the values.

import requests, json 

def AlphpaFetcher(from_currency, to_currency, api_key): 
    alpha_url = r"https://www.alphavantage.co/query?function = CURRENCY_EXCHANGE_RATE"
    final_url = alpha_url + "&from_currency =" + from_currency + "&to_currency =" + to_currency + "&apikey =" + api_key 
    req_ob = requests.get(final_url) 
    result = req_ob.json() 
    
    print("Realtime Currency Exchange Rate for", 
        result["Realtime Currency Exchange Rate"] 
                ["2. From_Currency Name"], "TO", 
        result["Realtime Currency Exchange Rate"] 
                ["4. To_Currency Name"], "is", 
        result["Realtime Currency Exchange Rate"] 
                ['5. Exchange Rate'], to_currency) 

if __name__ == "__main__" :
    from_currency = "USD"
    to_currency = "BRL"    
    api_key = "XXXXXXXXXX"
    AlphpaFetcher(from_currency, to_currency, api_key)

and return this

Traceback (most recent call last):
  File "c:\Users\Lucas\Desktop\teste.py", line 37, in <module>
    AlphpaFetcher(from_currency, to_currency, api_key)
  File "c:\Users\Lucas\Desktop\teste.py", line 19, in AlphpaFetcher
    result["Realtime Currency Exchange Rate"] 
KeyError: 'Realtime Currency Exchange Rate'

correct your URL construction: (note no spaces before=)

    alpha_url = r"https://www.alphavantage.co/query?function=CURRENCY_EXCHANGE_RATE"

    final_url = alpha_url + "&from_currency=" + from_currency + "&to_currency=" + to_currency + "&apikey=" + api_key 
    req_ob = requests.get(final_url)