This seems to be a mixture of the two solutions (2.1 and 2.2) that I recommended.
The point of 2.2 is to have a single EnumType class that can be reused across all entities.
My recommendations:

• create a new directory inside src/App/src, call it Doctrine or Types
• refactor src/Admin/src/Entity/EnumAdminStatus.php by moving it to that new directory and calling it EnumType
• register EnumType inside config/autoload/doctrine.global.php as before
• adapt Admin entity by setting the status property's type to EnumType::NAME

Note:
Once you run the migration and the fixture, executing the diff command will throw an error, complaining that in EnumType::getSQLDeclaration the key values does not exist (neither would default, but that's a coincidence that it exists in both the type definition and the database table). This happens because executing the diff command will compare the already existing status column with the definition found in the entity. It is the definition coming from the database that does not have the values key.
You need to dig further in order to find out how to fix this issue.