C1900universalk9mzspa1583m7bin — Link

No enough memory. Minimum required: 1024 MB, found: 768 MB Verify your router’s memory:

Critical for security. This image includes cryptographic capabilities: SSH, IPsec VPN, SSL, and AES/DES encryption. Without k9 , secure management protocols would be unavailable. c1900universalk9mzspa1583m7bin link

If you are studying or labbing without a contract, consider using Cisco’s DevNet Sandbox or IOSv images (which are sometimes freely available for non-production use). Never trust an IOS binary from an unverified source—your entire network’s security could depend on it. No enough memory