Google Drive is Google's file sync app that lets you store all of your files online alongside your Google Docs documents, and keep them synced with all of your devices.
Send the current campaign asset and question for brand review.
Your reviewer gets the current asset with a clear request, and your campaign task keeps the handoff in view.
Flag campaign assets reviewers cannot open before brand review.
Your review task shows file access problems before review starts. The owner sees what to fix.