You can download with this link
1) Unzip CometChat
2) Upload cometchat folder in your root forum directory
3) Go for installing cometchat https://yoursiteweb.com/cometchat/install.php
4) Go to Admin panel
Login => cometchat
Pass => cometchat
5) You have all Features but if you don't have all features go in the left to Settings and General
6) under License Key put this key D2KBK-1GXGT-3OELN-RMCN0-SFP9T and update (now you have all Features )
7) Go in your Theme and "Edit HTML and CSS" under Global Template Paste this code after this Tag <head> and save
<link type="text/css" href="/cometchat/css.php" rel="stylesheet" charset="utf-8">
<script type="text/javascript" src="/cometchat/js.php" charset="utf-8"></script>
8) Refresh your web page, enjoy
PS: don't forget delete install.php file and change login and password for admin panel
Troobleshooting:
1) My Admin panel isn't working correctely and cometchat not working
Go to Settings and General and under Base URL change with /cometchat/ or /forum/cometchat/ or change Where your forum is installed