As the question gives us a link to mega so we download the file/directory attached to it. In attachment we get a file named "flag.txt" that contain random words so it's going to be a cipher what what cipher? .Looking at the file we see cipher ends with = so it can be base64 and also the name of problem also gives this hint. So we decode that text with base64 but we get another random words ends with =. So may be this is loop of base64 cipher one cipher into another so to get text from that we write a python script as shown below
