LTSC (Long-Term Servicing Channel) is a specialized "one-time purchase" version of Office intended for commercial and government organizations that cannot use cloud-connected apps.

: Presentation tools with enhanced transitions and media support. : Comprehensive email and calendar management. : Digital note-taking and organization. Version 16.54 Specifics

To reiterate: You must be a Volume License customer.

When you see a LTSC for Mac ZIP file floating around (especially v16.54), you aren't looking at a piece of software. You are looking at a political statement. It says: "I refuse to rent my tools. I reject telemetry. I do not want my spellchecker to phone home to Azure."

The Mac version of Office has a tortured history. v16.x is the modern era (the "Office 2016 and beyond" codebase). However, v16.54 is a specific fossil.