alex1982 on "[Plugin: W3 Total Cache] FTP credentials don't allow to copy to file (+others)"

Any line starting with "cp" means: Copy a file. In your case(s), where you shall use the shell commands, just use an FTP-client like filezilla and copy the requested files. In detail: navigate to
mywebsite/wp-content/plugins/w3-total-cache/wp-content/
and download the file
advanced-cache.php, then navigate to
mywebsite/wp-content/
and upload the file there. Then set the write permissions for this file to 777, if you don't do so, the plugin tells you always to copy that file!

Do the same to other files, if requested.

If you get the message for the .htaccess-file, download that file (it's under mywebsite/.htaccess, open it with a texteditor like notepad++, look for the lines:
# BEGIN W3TC Page Cache core
# END W3TC Page Cache core
Put the requested part
(in my case, Version 0.9.3 it was the following) in between these lines and save your file and upload it. MAKE SURE to backup your .htaccess - file first, if you do make any error. It avoids freaking out :).

# BEGIN W3TC Browser Cache
<IfModule mod_deflate.c>
    <IfModule mod_headers.c>
        Header append Vary User-Agent env=!dont-vary
    </IfModule>
        AddOutputFilterByType DEFLATE text/css text/x-component application/x-javascript application/javascript text/javascript text/x-js text/html text/richtext image/svg+xml text/plain text/xsd text/xsl text/xml image/x-icon application/json
    <IfModule mod_mime.c>
        # DEFLATE by extension
        AddOutputFilter DEFLATE js css htm html xml
    </IfModule>
</IfModule>
# END W3TC Browser Cache

In my case there was some other code in between that lines, so I replaced them and it worked.

I recommend to NOT set the write permissions to 777 to the wp-config.php - file. If you did so, change them after your changes back to the original values.