Build a custom Drupal 9 group

Here is the full description of the work: Install OG module, and configure a new content type called Group as an OG Group. Implement a Pluggable entity view builder (PEVB) plugin to Full view mode of the new Group content type, similar to this example. Add to the PEVB plugin the following logic: Whenever a registered user will visit the group, it should offer to subscribe that user by greeting them with their name: Hi {{ name }}, click here if you would like to subscribe to this group called {{ label }}. Make sure to use OG’s API to check if the user is allowed to subscribe. Add a test to validate the functionality.