Export with LUT or IGST ?

Sir, some confusion about LUT, If the service export is a taxable supply, but zero rate. It means that the service export invoice does not include any tax because it is zero-rated. So which amount needs to pay in the form of IGST without LUT? If not then what is the purpose of taking LUT? If I don't have the LUT then do collect IGST (add Tax) in my service export invoice from international customers?

Dear sir,
We make export of service
We have taken LUT
In table 6A
Whether I have to select
With payment of tax then put invoice value in zero rate
Or
Without payment of tax
Put value zero rate
or
Put value 18%

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Sir please make a complete video on this if possible

Sir if possible please make one video on this topic I am merchant exporter.

Hello sir lot of confusions regarding lut.
Correct me if I'm wrong what I understood regarding lut is for ex:I'm merchant exporter I want to purchase goods from manufacturer so I will have to pay igst to manufacture so I will issue lut to my supplier I will not pay gst and will export the goods right?