QBO Intuit is cloud-based so it's obvious that you can't work upon it without a working internet connection. Check your internet connection before login to avoid any network issues.
It's a known fact that QBO Intuit works best with Chrome, so it won't be wise to try to launch it via another browser.
Having a separate user dedicated only for the QBO Online Login drastically decreases the login time and increase efficiency.
Delete cookies and caches from your browser, as these sometimes disrupt the QuickBooks Intuit Login process.
If you have an active firewall make an exception in it for the QuickBooks online as it may prevent you from Intuit QuickBooks sign in.