Run button greyed out on iOS application

Good evening,
I haven’t developed an iOS application before, but finally have a need. I have downloaded Xojo 2020 r2.1 (my license is for an earlier version) and Xcode 12.3. I have generated a simple Xojo test app but notice that the Run icon is greyed out. If I open a sample iOS Xojo app provided with the download I get the same result. If I write a sample iOS App in Xcode the iOS simulator operates correctly. I also notice that under the iOS navigation item no simulation devices are list.
Could anyone suggest what may be wrong?
Thank you.

I believe you have to open Xcode at least once to initialize the simulators.

I found the problem. Needed command line tools enabling in Xcode. Could not see it mentioned in documentation.

For reference, Xcode info is here:

https://documentation.xojo.com/topics/application_deployment/apple_requirements/xcode_setup.html

Thank you.