lot size issue for indices

I’m facing an issue with lot size calculation for indices in cTrader. When I set up my trade on TradingView and calculate the lot size, the value doesn't match when I enter it in cTrader.

For example, using a FundingPips account on cTrader with the NDXUSD (NAS 100) index:

• Margin: $2,000
• Risk: 1%
• Entry: 21,604.15
• Stop-loss Level: 21,549.24
• Profit Level: 21,840.41

On TradingView and other online lot size calculators, the lot size shows as 0.36 lots. However, when I enter 0.36 lots in cTrader, the P&L figures are different.

Could you please explain how to calculate the correct lot size for indices in cTrader?