It says that “Even Google cannot find this one”, so i decided to go to robots.txt file. https://ringzer0ctf.com/robots.txt

we can see disallow for this folder: 16bfff59f7e8343a2643bdc2ee76b2dc

let’s go there, and we found the password! https://ringzer0ctf.com/16bfff59f7e8343a2643bdc2ee76b2dc/

Flag: FLAG-G5swO95w0c7R5fq0sa85nVs5dK49O04i