This article will show you a couple of ways to join a Zoom meeting
To Join Zoom Meeting via Email Invite
Go to your email inbox and look for a Zoom invite from the meeting host. Click the Join Zoom Meeting link in the email.
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The link then takes you to the Zoom client . Click Open Zoom Meeting to download the Zoom client if you do not have it on your device.
Once the Zoom client is downloaded. Click Launch Meeting to join the meeting 
Click Join with Computer Audio to connect with computer audio.
Click Test Speaker and Microphone to check audio
Run Speaker audio check. Click Yes if sound is ok
Speak into your microphone to check audio
Once audio checks are done, click Join with Computer Audio to join meeting 
Open Zoom Meeting window to full screen
You are now in the meeting
To Join Meeting from Zoom Client
Open Zoom client and click Join tab 
Click arrow to show meeting list
Select the Zoom meeting you want to Join
Click Join to enter meeting
Note: A meeting must be in progress for an invitee to join.