List of issues.

[tunage]

#1 No where in the Instagram system is there an APP_KEY.

You have a client_id, but by asking for a KEY vs and ID, you completely throw people off.
#2 ../ makes you go backwards a directory. git clone imports to PHP-Instagram-API, so if a party goes backward, that won't work either. So your require statement is broke.
#3 using composer? you can't, nobody knows the project name to use. Your instructions completely fail here too.

{
"require": {
"cosenary/Instagram-PHP-API": "2.2.*"
}
}

produces:

Problem 1
- The requested package cosenary/instagram-php-api could not be found in any version, there may be a typo in the package name.
#4

Something went wrong :(

I have no clue what this is supposed to mean. zero error handling. Your guess is as good as mine. Anywhere you put a var_dump(), you can't get to the output.

your software is broken because your instructions are so poor.

[simplethemes]

@tunage this repo is "php-instagram-api/php-instagram-api". Your composer issues seem to stem from "cosenary/instagram" an entirely different repo.