You will need to know your existing cart table prefix. To find it Open cPanel and you should see:
1.Click the File Manager.
After clicking the File Manager, you should see:
2. Click public_html.
3. Click the installation subfolder name if you are installing AbanteCart in the subfolder instead of the root folder.
4. Click system.
5. Click config.php.
6. Right click config.php and click the View. It will open up a new page showing your cart database info.
7. This is your database prefix.
8. Open the sql file that you have downloaded to your computer.
9. Change these prefixes to the prefix that your cart installation use in number 7 above.
10. Finally save the changes.