What are Runescapes account and autominer? Let me tell you now. The Runscape accounts are login details to a character in the game that you can buy and it often comes with a stocked inventory of gold coins and items in addition to the most valuable thing, which is: skill stats.
Autominers are like macro programs. In simple words, they play Runescape for you. They click stuff and automatically mine rocks for you, for example.
Are these legal? No. These are against the Runescape rules, so I recommend not downloading and installing them at all, also because they might contain viruses. You can buy an account from a friend if you know they won't screw you over. But be careful because the account comes with personal information that the original owner can reset. Never use Runescape autominers or macros, because you'll end up losing your account to a ban or something.