Create folder as read only

Hi Juan, you can limit what someone can do within a task/Folder, but you can't create a fully read-only item. 

How to limit rights within the Workspace

• Collaborators - Collaborators are a free license type. This type of user can only do a few things within the Workspace (like change status, add attachments, and comments and a few more things). 
• Folder and Project Permissions - (this one's for Business and Enterprise accounts) Collaborators have limited rights within the entire Workspace, you can use Folder Permissions to limit someone's rights on specific Folders/Projects. 

Let me know if either of those sounds like they might help.