As of now, pre-update, sharing restricted files can be somewhat of a pain. You have to enter in the person’s email, have them accept, then you have to manage the permissions they have. But with the update, the Drive app lets recipients request access with a single tap, and file owners will be notified of the request instantly on the mobile device.
On the notification side of things, after the update, you will receive mobile notifications to alert you immediately when files or folders are shared with you and a single tap can take you right to them. Lastly, anyone can now preview documents, even if they do not have a Google account, as long as they are on an Android device.
The update is rolling out to Google Play Store now and if you're impatient and want to sideload it via APK you can hit the APKMirror link below :