Most Drive-to-Dropbox migrations go wrong in the same three places: shared drives with inherited permissions, files owned by people who have already left, and Google-native documents that do not have a direct equivalent.
1. Inventory before you move anything
Export a full file listing with owner, last-modified date and sharing scope. Anything untouched for two years is a candidate for archive rather than migration — this routinely cuts the volume by a third.
2. Resolve orphaned ownership first
Files owned by departed employees will silently fail or land in the wrong place. Reassign ownership in Drive before the migration starts, not during it.
3. Map sharing, do not copy it
Inherited permissions on nested Drive folders rarely reflect what the team actually needs. Use the migration as the moment to design team folders deliberately.
4. Convert Google-native files intentionally
Docs, Sheets and Slides convert to Office formats or stay as links. Decide per team — creative teams usually want the link, finance usually wants the file.
5. Run a delta pass after cutover
Users keep working during the migration. A delta sync on cutover weekend catches everything created after the initial pass.
Run in this order and a mid-size migration finishes over a weekend with no lost files.