Installation of real time sychronization clock

Hi, I wanted to install real time installation clock. So I wanted to know the link from where can we install this block for simulink. Because the block is available on simulink but when i run my project the error is displayed as "Installation of real time sync. block is required". If there is a requirement to install this block in which folder should this be installed so that matlab simulink can fetch its path without giving an error. BTW, I am using matlab 2017 version.