To install it, search MacKeeper on Google and then click on Because after experiments, I simply restore my Mac to the previous state without needing to reinstall macOS and all applications and without worrying about my data. Once I have a backup, I know I can install pretty much anything on my Mac, even viruses.
Note: One thing I always do before experimenting with any software is taking Time Machine backups. I decided to check it myself, and below is what I found in a Of user reviews calling MacKeeper a scam, a virus, or rogue software. Just browse Reddit or Apple forums, and you will find a lot