Download the latest SecureCRT for Linux Ubuntu 16.x 64-bit (scrt-8.3.0-1514.ubuntu16-64.x86_64.deb) from official Website 
Double click the downloaded .deb file, and install it through Ubuntu Software Center for ease.

Open a terminal (Ctrl+Alt+t) and download the perl script:
rana@Ubuntu16:~$ wget http://download.boll.me/securecrt_linux_crack.pl

Check out the SecureCRT installation path: 
rana@Ubuntu16:~$ whereis SecureCRT
SecureCRT: /usr/bin/SecureCRT 

Run the perl script on SecureCRT's installation path '/usr/bin/SecureCRT':
rana@Ubuntu16:~$ sudo perl securecrt_linux_crack.pl /usr/bin/SecureCRT

If the script is successful, the registration information output will be generated in terminal.
Now, run 'SecureCRT' command in terminal and follow the prompts to fill out the registration information output in 'Enter License Manually' Tab.
All Done!