Can't Login, error Warning: mcrypt_decrypt()

I purchased the software 30 minutes ago, after setting new password for the login its kinda weird that I can’t login.

Here’s the error message
“Warning: mcrypt_decrypt(): Key of size 3 not supported by this algorithm. Only keys of sizes 16, 24 or 32 supported in /home/_shared/inc/functions.php on line 303”

P.S. haven’t yet downloaded and installed the pro version since I can’t view the main page for the download link, I need to setup the software as soon as possible.

https://www.ads-software.com/plugins/social-networks-auto-poster-facebook-twitter-g/