I am also facing same problem. not able to figure this out. Also i gave all the permission inside installed package.
My request
Host: https://MY_SUBDOMAIN.rest.marketingcloudapis.com
POST /interaction/v1/events
Content-Type: application/json
Authorization: Bearer MY_OAUTH_ACCESS_TOKEN
{
"ContactKey": "abc123",
"EventDefinitionKey":"MY_API_EVENTKEY",
}
Error
Insufficient privileges to complete this action