Hi everyone ive just got this app to learn guitar its been a life long ambition (im 52)

Im dong the core learning thing from scratch and now upto chapter 3 at the daves riff secton , now i can play it when alone (odd mistake albeit) but when it comes to playing along with lisa ( the instructor) i cant seem to put 6 notes together and crumble for some reason

Can any of you give me any advice please its really doing my head in been at this bit for 3 days i just cant seem to get past the play along part lol