I really don’t think so. As I wrote, I ran a mal ware scan immediately after and had Apple support check the computer files too. I think I’m safe there.
You didn’t download malware. You downloaded a legit tool to access your computer. You need to find that software and delete it.
Do a search for the file you downloaded to your computer. Macs use .dmg files, so don't search just using that. Also, look at all recent downloads, as they may have spoofed the name of the file. Just because someone says you're clean, doesn't necessarily mean you're clean.
Rootkit installation can be automated, or an attacker can install it once they've obtained root or Administrator access. Obtaining this access is a result of direct attack on a system, i.e. exploiting a known vulnerability (such as privilege escalation) or a password (obtained by cracking or social engineering tactics like "phishing"). Once installed, it becomes possible to hide the intrusion as well as to maintain privileged access. The key is the root or administrator access. Full control over a system means that existing software can be modified, including software that might otherwise be used to detect or circumvent it.
Rootkit detection is difficult because a rootkit may be able to subvert the software that is intended to find it. Detection methods include using an alternative and trusted operating system, behavioral-based methods, signature scanning, difference scanning, and memory dump analysis. Removal can be complicated or practically impossible, especially in cases where the rootkit resides in the kernel; reinstallation of the operating system may be the only available solution to the problem. When dealing with firmware rootkits, removal may require hardware replacement, or specialized equipment.