Authenticate with the Classy (now rebranded GoFundMe Pro) API and list an organization's campaigns and transactions

Steps

1. Request API access/app credentials (client ID and secret) through the developer portal for your organization
2. Obtain an OAuth2 access token using the client-credentials grant against the token endpoint
3. Call the organizations/{id}/campaigns endpoint (or the equivalent campaign list resource) with the bearer token to list active campaigns
4. Call the organizations/{id}/transactions or campaigns/{id}/transactions endpoint to retrieve donation transactions, using pagination parameters for large result sets
5. Refresh the OAuth token before expiry using the refresh token or by re-requesting a client-credentials token
6. Check the deprecation schedule in the developer portal before building against any endpoint, since the platform is mid-rebrand