Short answer: you can't.
Zoom isn't opensource and doesn't provide a FreeBSD version. It does provide a Linux version, and it's probably possible to get that running on FreeBSD using Linux compatibility, but I assume it won't work with linux-c7-* ports and would require installing a Linux jail. Note however I never tried, this is just guesswork.
The only time I needed Zoom (for a conference I had to attend for work), I just installed it on Windows (running in a bhyve VM).