How can I access the files I created in my google project

Question

I have spent a lot of times creating a project in https://console.cloud.google.com, enabling the Drive API, creating server account credentials, and finally writing a small NodeJS integration allowing me to read and write files to Google Drive.

My intent is to be able to store files (organized in folders) on Google Drive from my server, and see them in the classic Google Drive desktop app with my Google account to check everything is fine.

My project seems correctly setup and I was able to create files from my NodeJS program (the files exist, I can list them with the same program), but I can't see the files anywhere in Google Drive with my Google account, with which I created the project.

I was expecting this to be extremely simple. That I would have a out of the box Drive UI allowing me to review the changes. In the documentation they say I can configure a UI integration but I don't know if this is what I am looking for or not. It seems complicated, talking about my "app" etc, while I just want a simple Google Drive UI for it !

Could anyone help me understand all this ?

Thanks