Okta and ionic, Post and get methods do not get token to return to ionic application

I have an Ionic app with Oauth 2.0 security. I have configured all the parameters for the request to Okta to obtain a secure login, the process is successful but from Okta they throw me the following error, leaving the app blocked and without access token:

POST https://dev-4896801.okta.com/oauth2/v1/token 401

{“errorCode”:“E0000022”,“errorSummary”:“The endpoint does not support the provided HTTP method”,“errorLink”:“E0000022”,“errorId”:“oaerVmUUGP8TZ2P-zDS7QfPwQ”,“errorCauses”:}

ERROR Error: Uncaught (in promise): HttpErrorResponse: {“headers”:{“normalizedNames”:{},“lazyUpdate”:null},“status”:401,“statusText”:“OK”,“url”:“https://dev-4896801.okta.com/oauth2/v1/token",“ok”:false,“name”:“HttpErrorResponse”,“message”:"Http failure response for https://dev-4896801.okta.com/oauth2/v1/token: 401 OK”,“error”:{“error”:“invalid_client”,“error_description”:“Client authentication failed. Either the client or the client credentials are invalid.”}}

What client authentication are you including in your token request/what grant type are you trying to use?

The configuration that is installed in the Ionic project is the following: ng add @oktadev/schematics. This library makes all the requests to Okta. Could you tell me what are the necessary settings for an Ionic app?