You can use your web browser and the invite link that the host sends you to get started.
Simply click on the meeting link and follow the prompts to join a meeting.
Inside the desktop app (or even the Zoom mobile app), you can join a meeting by inputting the Meeting ID sent to you by the host.
The host will find this in the upper-left corner of their Zoom window when they start or schedule the meeting.
One great feature about meeting IDs is that once a host sets a recurring meeting as the meeting option, participants will always be able to join the same meeting room by inputting the same personal meeting ID number.