Linking my Garmin 935 hr

I’m having trouble linking my hr to Zwift. I have the hr straps. Do I need a dongle?

For that watch it only broadcasts HR data via ant+. So you’ll need a USB ant+ dongle unless your device has ant+ natively

https://www8.garmin.com/manuals/webhelp/forerunner935/EN-US/GUID-57A88A77-3813-4E79-9DB1-FC95B06F01BA.html

Thanks I’ll give it a go