You will need to download the Zoom desktop client (app) onto the device you're going to use to attend the class sessions.
If you find that it's acting up, delete it and download the latest updated version (sometimes new updates make older versions get quirky)
For your screen name, please use a classroom appropriate name that will clearly indicate who you are (I use the waiting room feature on Zoom, and if I can't figure out who you are, I won't admit you to the class).
If you need to try and save some bandwidth, you can be available on audio but have your video off. Realize that I will ask you questions, however, to make sure you're there and participating.
Try to find a quiet place to do your Zoom sessions.