Looking for A Programming Guide Recommendation

This is Fleck James, I am a PHP web developer, I have my own small web development agency in Ohio, US. The reason to come to this platform is that my website is having an issue with data importing, I have a client who has an eCommerce business website on the Shopify platform, He had decided to move his business to a new website based on PHP Laravel, The website is ready but the problem is Shopify isn’t allowing us to Import full data which is in thousands. I have researched on the internet & found a useful laravel PHP guide which has helped me greatly. but the data has not been imported completely. Is there anyone who could help me with this problem? Any tutorial or guide would be helpful as well.