What is the process for sending a DMCA complaint? And do you have to be a registered company/business in order to send one?
You don't need to be a registered business to send a DMCA complaint; you just need to be the owner of the infringed content or the authorized agent of the owner of the infringed content. If you send a DMCA complaint which turns out to be incorrect, the person who you have accused of infringing on the copyright can sue you. See Consequences of Filing a False DMCA Takedown Request. There's a free DMCA takedown request formatter in my signature line.