Since you aren’t synced already, the easiest method is #1 (Full Storage Access · ankidroid/Anki-Android Wiki · GitHub) –
- Backup your AnkiDroid folder
- Install a github parallel build, which can still access the old file location
- Sync to upload your collection to AnkiWeb, which it is good to be doing anyway, so you have a backup! (AnkiDroid 2.17 User Manual)
- If you have a lot of media, it may take a few tries for all of your media to sync
- Then in your main install, setup syncing to download your collection from AnkiWeb