When trying to install ruby 2.3.3 it fails with issues relating to OpenSSL. I managed to get aroiund the issue by installing OpenSSL seperately and pointing the ruby 2.3.3. install at the OpenSSL install.
I don't know what Ruby is officially supported for build, but I use 3.0.1 with no trouble.
2.3.3 is quite old, and actually withdrawn from distribution, I think for security issues. The closet Ruby officially released is 2.3.4. But I think you will have trouble installing 2.3.4 as well (see below).
Keep in mind the Ruby on your system is not the Ruby used in Rhodes. The Ruby on your system is used only as part of the build process, and the Rhodes Gem has inside it a customized Ruby used in your app.
In fact, the Ruby used in your app is Ruby 2.3.4.
And, so, I try to keep Ruby 2.3.4 available on my system (with rvm) because I often develop device-independent code snippets (like algorithms) that I will use in an app in a simple command-line app for ease of debugging, and of course it is best to use the same version that Rhodes uses in your app to avoid surprises.
I found the closest version I was able to install is 2.4.10.
I think though you should be successful building with 2.7.3 or even 3.0.1.