Cochlear Hearign Dervice issues using Zoom

II had issues with using Zoom this past Friday, My mom had a meeting with her lawyer and my mom is hard of hearing loosing her hearing actually, my mom has her hearing aide connected to her phone and with calls it works well. When we tried to use her phone with Zoom my mom couldn’t hear the lawyer. I also found out that Zoom has closed caption that was not turned on by the host that would help my mom with the meeting. Can anyone suggest what I should do to fix this issue my mom is facing please. My mom needs to hear the lawyer talk and then a meeting with the City of New York regarding accident so this is super important. 

Thanks

Clark