There are many WordPress plugins available in the market. However, we would suggest you check here for the list of best rated WordPress security plugins and secure your WordPress website and blog from all the Major Malware attacks and from Hacking.
Once you purchase this Plugin, you will get an email confirmation along with the link to login to the Solid WP Member Panel, where you can download your Solid Security plugin zip file. You will be also given the set of instructions on the same email.
Incase you need to contact Solid WP support, you can always contact them either from https://solidwp.com/support/ or through Email. They will be always responding you for any querries.