I am using Edge and Safari browsers of Saucelabs through Zalenium as below.
Microsoft Edge
{type : msedgedriver, webDriverSession : {capabilities : {browserName : MicrosoftEdge}, desiredCapabilities : {browserName : MicrosoftEdge}}, start : false, webDriverUrl : https://username:password@your_zalenium_host.com/wd/hub}
Safari
{type : safaridriver, webDriverSession : {capabilities : {browserName : safari}, desiredCapabilities : {browserName : safari}}, start : false, webDriverUrl : https://username:password@your_zalenium_host.com/wd/hub}