What version do you have? I read this on their site:

Important Note for Studio One Artist Users: 3rd party VST integration is not supported in Studio One Artist version 1 or version 2. You must have registered and activated Studio One as the Producer or the Professional versions to have VST support with Studio One. 

Here is a list of free VST reverb plugins:

https://www.soundshockaudio.com/10-best-free-reverb-vst-plugins/

Here is a list of free VST delay plugins:

https://thehomerecordings.com/free-delay-plugins/

@robert I have Artist v4 with Studio One Rewire Plugin Support. Allows  me to download VST/AU plug-ins.

Posted by: @robert

Here is a list of free VST reverb plugins:

https://www.soundshockaudio.com/10-best-free-reverb-vst-plugins/

 

Here is a list of free VST delay plugins:

https://thehomerecordings.com/free-delay-plugins/

Thanks for the lists. Appreciate it...