gTove does not have its own dedicated servers, but instead uses your Google Drive to store your map and mini images and JSON data files containing the details of your scenarios. These are added to your Drive when you create them through the app, by uploading images, defining grid scales, setting scenario names etc. This gives each user ownership over their own data, and the convenience of browsing their files using Drive.
When you first use the app and grant it permission to access your Drive, the app creates a top-level folder, gTove Virtual Gaming Tabletop, which is where it subsequently places all its files (the top-level folder can safely be renamed or moved elsewhere in your Drive if you like, although you'll need to reload gTove afterwards). The app is not able to access any part of your Drive except for files and folders it creates, and it only creates files and folders under this top-level folder. It may also access files under other users' top-level gTove folders, if they share them with you (for example, if you are a player, when your GM sends you a link to a shared tabletop with maps and minis that they set up in advance, your gTove app will read the files from the GM's Drive).
gTove requies "drive.file" permission to do its work, which allows the app to have "per-file access to files created or opened by the app." In other words, gTove is allowed to read and write files on your Drive that it creates on your behalf, when you upload and define things from within the app itself.