For anyone who doesn’t know what ‘registering for DMCA notification’ means, you’re after https://www.copyright.gov/dmca-directory/

That said, there’s no particular requirement that a DMCA notice be sent to you even if you have a registered agent and some reporters will send it to the abuse contact for the IP netblock you’re hosted on regardless of registration, so you may want to make sure you understand what steps your provider may or may not take when they get a DMCA notice before you actually get a notice.