Which GST to charge(Whether exempt or chargeable)

An exhibition event will be held in Maharashtra for which a foreign participants will be admitted.
1.The participants are unregistered.
2.Invoices will be raised in USD.
3.Payments will be received in USD.

Query
1.Whether this will be an export and exempt transaction? (LUT has been filed assuming export transaction).
2.If not export then whether to charge IGST or CGST & GST?
3.What will be the scenario of ITC in such a case?