They told me I just need to extract flag but I don’t know what that means?! flag.rar
After extracting the first file with an online .rar extractor, I realized that it was probably just a bunch of nested compressions/zips, given that the next file was a .tar.xz file.
The easiest solutions are to either use 7-Zip File Manager or just binwalk -eM flag.rar on Linux (-e means extract, -M is basically recursive), which results in a final file, flag.gif.
Use a hex editor and Ctrl+F for “INTIGRITI” or do grep "INTIGRITI" flag.gif on Linux to get the flag!
INTIGRITI{fl46_3x7r4c710n_c0mpl373}