rbenv: ruby: command not found The `ruby' command exists in these Ruby versions: 2.5.1

I installed ruby 2.5.1 and rail 5.2.1 on CentOS7 . I have an existing rail project which is 3.2.13. Now the existing rail project does not run in my local environment.
I create a new project on rail and it runs

[root@localhost html]# cd ruby_rails/
[root@localhost ruby_rails]# bin/rails server
=> Booting Puma
=> Rails 5.2.1 application starting in development 
=> Run `rails server -h` for more startup options
Puma starting in single mode...
* Version 3.12.0 (ruby 2.5.1-p57), codename: Llamas in Pajamas
* Min threads: 5, max threads: 5
* Environment: development
* Listening on tcp://0.0.0.0:3000
Use Ctrl-C to stop
Started GET "/" for 127.0.0.1 at 2018-10-06 21:43:25 +0900
Processing by Rails::WelcomeController#index as HTML
  Rendering /root/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/railties-5.2.1/lib/rails/templates/rails/welcome/index.html.erb
  Rendered /root/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/railties-5.2.1/lib/rails/templates/rails/welcome/index.html.erb (11.4ms)
Completed 200 OK in 188ms (Views: 131.5ms | ActiveRecord: 0.0ms)

But I have an existing project on rails 3.2.13 that does not run on my local environment

[root@localhost html]# cd rehome_navi-master/
[root@localhost rehome_navi-master]# bin/rails server
rbenv: ruby: command not found

The `ruby' command exists in these Ruby versions:
  2.5.1

I really need to run this project. please help me.