To create subscriptions on EventSub you msut use an App Access token, as the error states
App Access is also referred to as Client Credentials
You must first have created a user access token with the required scopes.
I wrote a blog post about it here How does Twitch’s new EventSub work? – Barry Carlyon
Essentially you use two access tokens of two different types. One to get permission to read, the second to actually talk to eventsub
I also redacted your token, you should never leak a generate token or refresh token.