Unable to run exported recorder script on Firefox

I’ve tried to run an exported (groovy)script from Katalon recorder in Katalon Studio 5.8.6. The test should be executed in Firefox (on Mac), but will not start - according to the error message below.

I am totally new at this - so I would be very grateful for any input. Thank you!

Test Cases/Script FAILED because (of) (Stack trace: com.kms.katalon.core.exception.StepFailedException: Unable to open browser with url: ‘https://www.katalon.com/’ (Root cause: No driver is set for execution.)

at com.kms.katalon.core.keyword.internal.KeywordMain.stepFailed(KeywordMain.groovy:36)

at com.kms.katalon.core.webui.keyword.internal.WebUIKeywordMain.stepFailed(WebUIKeywordMain.groovy:65)

at com.kms.katalon.core.webui.keyword.internal.WebUIKeywordMain.runKeyword(WebUIKeywordMain.groovy:27)

at com.kms.katalon.core.webui.keyword.builtin.OpenBrowserKeyword.openBrowser(OpenBrowserKeyword.groovy:81)

at com.kms.katalon.core.webui.keyword.builtin.OpenBrowserKeyword.execute(OpenBrowserKeyword.groovy:67)

at com.kms.katalon.core.keyword.internal.KeywordExecutor.executeKeywordForPlatform(KeywordExecutor.groovy:53)

at com.kms.katalon.core.webui.keyword.WebUiBuiltInKeywords.openBrowser(WebUiBuiltInKeywords.groovy:60)

at com.kms.katalon.core.webui.keyword.WebUiBuiltInKeywords$openBrowser.call(Unknown Source)

at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48)

at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113)

at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:125)

at Script1542634415004.run(Script1542634415004.groovy:31)

at com.kms.katalon.core.main.ScriptEngine.run(ScriptEngine.java:183)

at com.kms.katalon.core.main.ScriptEngine.runScriptAsRawText(ScriptEngine.java:108)

at com.kms.katalon.core.main.TestCaseExecutor.runScript(TestCaseExecutor.java:294)

at com.kms.katalon.core.main.TestCaseExecutor.doExecute(TestCaseExecutor.java:285)

at com.kms.katalon.core.main.TestCaseExecutor.processExecutionPhase(TestCaseExecutor.java:264)

at com.kms.katalon.core.main.TestCaseExecutor.accessMainPhase(TestCaseExecutor.java:256)

at com.kms.katalon.core.main.TestCaseExecutor.execute(TestCaseExecutor.java:200)

at com.kms.katalon.core.main.TestCaseMain.runTestCase(TestCaseMain.java:99)

at com.kms.katalon.core.main.TestCaseMain.runTestCase(TestCaseMain.java:90)

at com.kms.katalon.core.main.TestCaseMain$runTestCase$0.call(Unknown Source)

at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48)

at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113)

at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:149)

at TempTestCase1542698806475.run(TempTestCase1542698806475.groovy:22)

at groovy.lang.GroovyShell.runScriptOrMainOrTestOrRunnable(GroovyShell.java:263)

at groovy.lang.GroovyShell.run(GroovyShell.java:518)

at groovy.lang.GroovyShell.run(GroovyShell.java:507)

at groovy.ui.GroovyMain.processOnce(GroovyMain.java:653)

at groovy.ui.GroovyMain.run(GroovyMain.java:384)

at groovy.ui.GroovyMain.process(GroovyMain.java:370)

at groovy.ui.GroovyMain.processArgs(GroovyMain.java:129)

at groovy.ui.GroovyMain.main(GroovyMain.java:109)

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

at java.lang.reflect.Method.invoke(Method.java:498)

at org.codehaus.groovy.tools.GroovyStarter.rootLoader(GroovyStarter.java:109)

at org.codehaus.groovy.tools.GroovyStarter.main(GroovyStarter.java:131)

)