Hi KS1966,
It's good to see you posting today. I'm happy to answer your question about using an app.
You can access your QuickBooks Online company using a browser on your computer or your mobile devices. However, if you want a faster way to access your account, you can use a mobile app. It's not necessary, but it's more convenient.
I'm adding these articles for your additional reference:
Feel free to go back to this thread if you have other questions in mind.
