Any files that you want the client to download (that are not handled by another means - ie. maps, sounds) can be placed in this file
Edit the file $BASE/cstrike/cfg/mani_admin_plugin/downloads.txt
An example of the file is here
"downloads.txt"
{
// Add any files you wish to have downloaded to a clients system in here
// The key can be any name you wish.
// The value must be the location on your server of the file
"downloads"
{
// "my_file" "materials/decals/custom/mani_admin_plugin/mani_logo.vmt"
}
}