the module Group-Based Pricing (com.zengenuity.civicrm_groupprice) can't be enabled in Joomla. I copy the files from https://github.com/zengenuity/civicrm_groupprice into the media/civicrm/files and the module is still red in the page "Administer->System settings->Manage Extensions". The civicrm was moved from the Drupal site into the Joomla.
Can you confirm that's the correct directory for extensions by going to Administer menu » System Settings » Directories and looking at the Extensions directory listed there? It may also need to be updated from the Drupal location if you copied the database. If there's a token like
[civicrm.files] you can click the question mark in the blue circle in the text at the top of the page to see what that token resolves to.
If the directory is correct, it's likely a file permission issue.