问题是您要查找的元素在iframe中，因此您需要切换到iframe才能使用它们。
代码工作：

# Needed libs
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
from selenium.webdriver.common.by import By
from selenium import webdriver

# Initiate the ddriver and navigate
driver = webdriver.Chrome()
driver.maximize_window()
driver.get('https://estrelabet.com/ptb/games/detail/casino/demo/7787')

# We save the iframe where the elements you want to get are located
iframe = WebDriverWait(driver, 10).until(EC.presence_of_element_located((By.CLASS_NAME, "iframeDefaultSize")))

# We switch to that iframe
driver.switch_to.frame(iframe)

# Once we switched to the iframe, we can get the elements you wanted
blocks = WebDriverWait(driver, 10).until(EC.presence_of_all_elements_located((By.XPATH, "(//div[@class='payouts-block'])[1]//app-payout-item/div")))

# For every element you show the text
for block in blocks:
    print(block.get_attribute('textContent'))

如果在使用iframe之后，你想使用iframe之外的其他元素，你需要回到主框架，你可以这样做：

driver.switch_to.default_content();