You can get xpath/id of popup element and buttons, using these you can perform action on these buttons.
@findby(id="android/button1")
WebElement allow_button;
public void clickonAllow()
{
allow_button.click();
}
As per requirement you can click on button "Allow" / "Deny" or "Accept" or "Reject"
In web you can try driver.switchTo().alert().accept(); or driver.switchTo().alert().deny();