How to install ext-xsl package?

Question

PHP

Merry Christmas guys!
I have such a nuance - joxi.ru/5mdd9zBhkg9Ywm
I put this package not under root with the apt-get install php5.6-xsl command, I reboot the server and still writes that the argument is disabled, what should I do? on various forums I looked at what and how, but very little was said about this error and in principle one solution is installation using the above command!
Help Plaz!!!

Answer 1

I put this package not under root with the command apt-get install php5.6-xsl

And it is necessary under the root (better through sudo).
And what does the composer have to do with it? Either apt-get or composer.