Here are a few options for using Zoom within Slack. You can type any of these shortcuts as a Slack message.
Zoom Shortcuts in Slack:
/zoom Start a meeting
/zoom meeting [topic] Start a meeting with topic
/zoom join [meeting id/personal link name] Join a meeting using meeting ID/personal link name
/zoom join me Join a meeting using your personal meeting ID
/zoom call [@contact/phone number] Start a phone call with a contact or a phone number