fpdf-laravel | A package for Laravel to implement the FPDF class | Build Tool library

You are using an implementation for the Laravel framework that binds an instance of FPDF to the service container. Using app('FPDF') returns you a new instance of FPDF, which is pretty much the same what new FPDF() would do.

The require way of using it is framework agnostic and would be the way to use FPDF if you are just using a plain PHP script. While you could use this way with Laravel too, why would you want to do that?

The reason the require does not work, by the way, is that the fpdf.php file is not found from where you call it. It would be required to sit in the same directory unless you give it a path. Considering you installed it using composer, the fpdf.php script, if any, should sit inside the vendor directory.

However, just go with using the service container. The line $pdf = new FPDF('L', 'mm','A4'); just creates a new instance of the FPDF class and initializes it by passing arguments to the constructor, these being 'L' for landscape orientation, 'mm' for the measurement unit, and 'A4' for the page size. Without knowing the package you use and having testing it, you should also be able to set them equivalently by calling: