Ableton Live Sound - Help!

Hi all,

me and my tutor are having serial issue with regards to me hearing what my tutor is playing through his Ableton live (music production DAW). 

he can hear mine when i share screen, but it wont work from his. 

i have to then do the meeting from my phone which is so frustrating. it appears to be my laptop or settings, because i've tried it with two different tutors.