Follow the steps below to enable self registration:
Log in to your Moodle site as the admin.
On your home page, go to the Site administration menu under the Settings block, and select Plugins, as shown in the next screenshot:
Then select Authentication and then Manage authentication. You will then be at the screen shown below:
In the Manage authentication screen, first make sure that the Email-based self-registration is enabled. You will know if something is enabled if the eye next to it is open.
Click the Settings link to the right of the Email-based self-registration setting. This will take you to the settings page for the plugin.
On the plugins setting screen, set the Enable reCAPTCHA element to Yes. ReCAPTCHA is a system for preventing spammers from using programs to create accounts on your system. It generates a random string of numbers and letters that are difficult to process with code.
Next, on the same screen, scroll down to the Common...