Yes. For output (MacBooks) you can use any USB to hdmi-adaptor or dongle, I use this by Apple. Notice: display port to hdmi does only support video (without audio, at least mine not)
On the iMac, you have to Download BMD Desktop Video Drivers. Ultra Studio Mini Recorder needs to be configured for hdmi Input. (I think SDI is set as factory default). It‘s just two clicks after starting the application.