Can you please verify that auth.json file is there in root directory ?
If not - create auth.json file in the root directory and then add public key and private key in that auth.json file !
Then check - it might work
ok - i understand !
I think this post have same issue - https://magento.stackexchange.com/questions/102013/magento-2-enterprise-install-issue
Which you are facing and it have solution as well - kindly refer this it might help you !