Angular and Vue are both available under the MIT license, while React comes with the BSD3-license. In some older blog posts, the use of React is not recommended because of its patent file. This should not be a problem anymore, because Facebook has since changed the license — you can read more about it in this Github issue.
Tip: To make a controller/view/style file within a folder, you don’t have to create these files manually, or move them to a manually created folder. Just right-click on your project, choose “New > Alloy Controller” and then type “profile/page.js” as the name to create a controller named “page.js” within the “profile” folder. It will create the folder if it doesn’t exist yet, and will also do the same for a view and style file.