In order to use GitHub OAuth you must register your application at .
Example application configuration:
php
'components' => [
'authClientCollection' => [
'class' => 'yii\authclient\Collection',
'clients' => [
'github' => [
'class' => 'yii\authclient\clients\GitHub',
'clientId' => 'github_client_id',
'clientSecret' => 'github_client_secret',
],
],
]
...
]