Hi, I'm trying to make a REST API call at:

https://....salesforce.com/services/apexrest/...

but I'm getting this error:

{'message': 'You do not have access to the Apex class named: OutboundInterfaceRunRestService', 'errorCode': 'FORBIDDEN'}

It works if I use an admin user, but not with another user. What permissions should I give this user?