You need VIP to use mirror mode. The client you will need to use for a Jagex account is the Legacy client. Basically the old original client. You will then open Jagex launcher and open osbot as well. In the launcher select Legacy client and the character name you wish to use. Lunch the client from the launcher and then press mirror mode on osbot before logging in. Now you will have osbot open and it will ask you for account info. Select default account and press ok on the notice message that comes up. This will then open a screen on osbot saying searching for client to inject into. It should then "mirror" the client and you will be able to bot. I think this site needs an updated tutorial section. Let me know if you get stuck anywhere. When I get home tonight i can add pictures if need be. Also make sure mirror mode box in NOT ticked when pressing mirror mode tab.
TLDR
>Open Jagex Launcher+ OsBot at the same time
>Launch Legacy Client
>Click mirror mode on Osbot
>Click default account on Osbot after clicking mirror mode
>Mirror mode should now be working