ATM withdrawal in Thailand and DCC


I am visiting Thailand next week and was planning to use Niyo Global SBM card to withdraw money there. I have a couple of questions:

From info I have gathered, I would be charged Rs. 100 + GST and ATM charges for withdrawal, correct? How do i know usd inr conversion rate to be used in USD transaction by niyo - #2 by Deepak
The amount dispensed would be equal to whatever exchange rate the Niyo app is showing, nothing more, nothing less. Is this correct?

Also, from the forums, I have come across situation where ATM withdrawal was not working due to DCC being disabled. Can you please confirm if this is true? Because if it is then I’d have to make other alternate arrangements. What is Dynamic Currency Conversion (DCC) and why are they declined on your Niyo Global card?