Box V3 module not working

I am trying to watch a folder using the V3 Box V3 module. The only inputs are for a Client ID and Secret ID. In I created an app called “Make / Integromat V3” which has a Client ID and Secret ID. When I click “SAVE” to create the connection I get the following error message:

Error: redirect_uri_mismatch

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I don’t know what I am doing wrong.