Cannot find OAuth 2.0/1.0 authorization method in SoapUI HTTPS request

Hi! 

I want to use SoapUI 5.6.0 to send HTTPS requests, and I need to use OAuth 2.0 authorizations with it. I tried to follow the the instruction at the following reference

https://www.soapui.org/docs/oauth2/reference/add-authorization/

The reference shows that I should be able to see Auth 2.0/1.0 options in the dialog below.

However, I could only see the options like below:

I tried several attempts to get access to OAuth options:

** install alternative versions of SoapUI (versions 5.5.0 and 5.3.0)

** use other machines

** create new SoapUI workspace with new project, following the posts at https://community.smartbear.com/t5/SoapUI-Open-Source/Oauth2-missing-from-list-of-authentication-methods-any-ideas-why/td-p/136383

After trying all these, I still cannot see OAuth 2.0 option.

How can I fix it? Thank you!