Tuxguitar: Can't sign up with them

[arpegadream]

I installed Tuxguitar but when I try and sign in with google or facebook, the only options that appear, I get error webpages like this:

Php Warning: require_once(__DIR__/composer/autoload_real.php) [function.require-once]: failed to open stream: No such file or directory en /var/www/virtual/tuxguitar.pw/community/htdocs/c/google/vendor/autoload.php linea 5

Fatal error: require_once() [function.require]: Failed opening required '__DIR__/composer/autoload_real.php' (include_path='.:/usr/share/php:/usr/share/pear') in /var/www/virtual/tuxguitar.pw/community/htdocs/c/google/vendor/autoload.php on line 5

And with the other option:

Parse error: syntax error, unexpected T_STRING, expecting T_CONSTANT_ENCAPSED_STRING or '(' in /var/www/virtual/tuxguitar.pw/community/htdocs/WEB-INF/modules/sharing/classes/com/web/modules/sharing/actions/public/SFacebookLoginAction.inc on line 5