Are you certain the file is in the /zonewalker-acar directory on your device's internal storage (not the SD card)?
Side thought- Be sure there aren't any additional/duplicate folders in that area. Example; I've received reports where users have a folder for "Backups" and or "zonewalker" or any other variants of names, and then group their data into them. aCar isn't able to access the files unless the files are in the zonewalker-acar folder.
So if you plug your phone into a computer and open the internal storage and then navigate to the backup file, double check the path it takes to get there.
It SHOULD look something like: Computer\SAMSUNG-SM-G900P\Phone\zonewalker-acar\aCar-auto-040715-0609.abp <that would be the file you're going to try to import back into aCar*
Just be sure it does NOT look something like: Computer\SAMSUNG-SM-G900P\Phone\zonewalker-acar\acar\randomfoldername\backups\somethingsometh ing\aCar-auto-040715-0609.abp (emphasis on the sub-folders)
If you do have random folders between /zonewalker-acar and your files, then move the file up and out of the sub folders and into the main(parent) zonewalker-acar folder.
Then- Open aCar -> More Options ->Import/Export -> Full Restore
Ensure you select the most recent ABP from the drop down and then "Start Restore".
If you continue having trouble, please send me a screenshot of your folders so I can verify there aren't any additional subfolders getting in the way of the importer. Also, please send me your backup file so I can attempt to replicate your issue on my end.
You can email the Help Desk (and attach your backup file/screenshots) by the Contact Us link within the app.