Class not found

I just started working on PHP and used Composer to integrate a package. Then as shown in the figure, why this class can never be found. No errors are reported in the compiler.

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I just started working on PHP and used Composer to integrate a package. Then as shown in the figure, why this class can never be found. No errors are reported in the compiler.

I just started working on php, and I have never seen this autoload.
When I looked at the way of php, there was a sentence that made me realize the error. The way of php
require 'vendor/autoload.php';
Added this sentence and it was successful. .

Is there no requirement?

The path is wrong, try removing a MediaInfo again.