Your issue is very straightforward here — you don’t have enough USDT to buy anything.
From your screenshot:
Available balance: 0.00000361 USDT
Max Buy: 0 NIGHT
That amount is basically zero, so the app disables your ability to purchase.
Why this happens
The minimum trade amount on Binance is usually around 5–10 USDT (or more depending on the pair)
Your balance is far below that, so the system won’t allow the order
How to fix it
You need to add more USDT to your Spot wallet:
Option 1: Deposit crypto
Go to Assets → Deposit
Choose USDT
Send USDT from another wallet or exchange
Option 2: Buy USDT via P2P
Go to P2P
Buy USDT using local payment methods (bank, Easypaisa, JazzCash, etc.)
Option 3: Transfer funds
If you already have funds in Funding / Futures wallet, transfer them to Spot wallet
After adding funds
Once you have at least 5–10 USDT, you’ll be able to:
Enter an amount
Click Buy NIGHT
Complete the trade
If you want, tell me how you plan to add funds (P2P, bank, another wallet), and I’ll guide you step-by-step.