Once you purchase the CLEAN Premium Pack from the HubSpot marketplace, it will be instantly be added to your account and ready to use. If you're an agency working with a client, be sure you are logged in to their portal prior to making the purchase.
"Cloning" is a term that HubSpot uses for making a duplicate copy. You can clone templates, files, modules, etc. Prior to making any major modifications to them, I highly recommend cloning the originals so that you always have an untouched copy.