Most LazyDFU startup problems can be categorized before they are “fixed.” Start with file type, loader, game version and the first meaningful error in the log. Randomly removing files can hide the actual compatibility problem.
Problem 1: the source ZIP is in the mods folder
The provided master.zip download is a repository archive. If your loader expects a compiled mod JAR, a source ZIP will not function as a normal installed mod. Obtain or build the appropriate artifact for the target version.
Problem 2: loader mismatch
The original project is Fabric-focused. Putting a Fabric mod into a Forge or NeoForge instance normally produces a loader error or the file is ignored. A Forge-capable port is a separate compatibility choice.
Problem 3: Minecraft version mismatch
A mod built for a different Minecraft range can fail dependency checks or break at runtime. Match the exact release metadata, especially in older packs where small version changes affect loader APIs.
Problem 4: conflict or stale configuration
Temporarily test with a minimal mod set, keep the original crash log, and add optimization mods back one at a time. This isolates interactions without destroying evidence needed to diagnose the first failure.
Related next step
Use the compatibility information above before choosing a download. If you only have the supplied master.zip, remember that it is source code rather than a normal mods-folder JAR.