I’m using standard tuning, however the entire guitar is tuned down one tone. So, when you see my hands in a D chord shape it’s actually a C chord! And all the jams so far are either in the key/scale of C or G. It will tell you at the top of each associated lesson document what key/scale the particular tune is in.
Most of the jams also have the chord progression notated on the lesson pdf too. So if you show that to your mates they should be able to play along with you. Even if they don’t play exactly like I do, it will still work well 🙂