Don't feel bad for the mentor, we're here to help. If you needed help with a particular area then that's exactly what the mentor would be there to help you with, at your own pace
There's no commitment for you to then apply for the graphics team, it is all to help you become a better artist & then if you do wish to apply you hopefully will have the knowledge to help you with that - as well as someone to contact to ask for tips & help if you need or want it when you do