MCrypt required & SSH to fortrabbit get Permission denied (publickey)

Hi, this is my first time using an app hosting with terminal, usually normal shared hosting, i have a local laravel 4 directory that i've been working on since a year now, i setup a fortrabbit app but when i pushed messages on the git bush stopped flowing with this error :

 Mcrypt PHP extension required.

 Script php artisan clear-compiled handling the post-install-cmd event returned with an error
 - - -


A B O R T E D

 !! Failure in build execution (fortrabbit.yml): Failure in composer execution. Please try again later.

To git@deploy.eu2.frbit.com:test-app.git
+ f2b83fd...163505e master -> master (forced update)
error: failed to push some refs to 'git@deploy.eu2.frbit.com:test-app.git'

i thought i had to activate the Mcrypt PHP extension manually via SSH but it doesn't let me even if i have 4 SSH keys on the fortrabbit and i get this message :

User@User-PC MINGW64 /c/wamp/www/laravel (master)
$ ssh test-app@ssh1.eu1.frbit.com
Permission denied (publickey).

it's been 2 days now and my 3 days trial on fortrabbit is going to end without having tryed to see anypage, and i'm getting # server error : 500