Sample Code:
<aura:component implements=”lightningsnapin:prechatUI” controller=”PreChatController”>
If you are using Site, then do the below steps.
1. Go to the Site.
2. Click Public Access Settings.
3. Add the Apex Class to the Apex Class Access.
If you are using Experience/Community Cloud, then do the below steps.
1. Go to Builder.
2. Go to Settings.
3. Go to General and open the Community Profile.
4. Add the Apex Class to the Apex Class Access.