Unable to Mutiply using General Caster app

Does anyone have any experience with General Caster app.

I have a “End Date” formula column which is taking into account several other columns and populating “End Date” from “Start Date”. But I need to use this End Date data in other integrations which is not allowing since it is formula column output. Hence I decided to use General Caster app. but it does not seem to be working for me. I have tried to reach the app developer support but no reply since a week now. Can anyone help. I have followed their documentation to “T” but except the first one, none of them seem to be working for me. Can anyone help. I am trying to multiply two numbers and cast it to “Numbers” column.