Microsoft .NET Framework 4.5 Offline Installer is available for Windows 7 SP1 (64-bit) through the Official Microsoft Download Center
No. .NET Framework 4.8 is backward compatible with nearly all applications designed for 4.5. However, if a specific legacy program still fails to run, you may need to enable the “.NET Framework 3.5” feature (for older 3.x apps) or contact the software vendor for guidance. Microsoft