I have the same error “interest error (code: 403) with message: Apps with Trial access may not create Pins…” But looking at Pinterest link (https://developers.pinterest.com/docs/getting-started/access-tiers/#upgrade-your-app-to-standard-access) They want me to send a video about how the integration works. I don’t know your internals so how do others who use your plugin get this to work?
