Do you want to automatically give access to specific contents of your site to all users who register? You can do that!
First of all, make sure you create a membership plan that includes all the contents that you want to show to registered users from YITH > Membership > Membership plans > Add new plan:
Please, refer to this page for the plan configuration details.
Then, in the plugin general settings (YITH > Membership > General Options), you will be able to enable an automatic plan on registration and pick one that you have previously created:
Now, every new registered user will automatically get access to specific contents!