If using offline mode, type any username. For premium, enter your Microsoft or Mojang credentials. Then choose a Minecraft version (e.g., 1.8.9 for PvP, 1.12.2 for mods, or 1.20+ for latest features if Java allows).
Follow this step-by-step guide to get working correctly. File name- EasyMC-Launcher-Windows-32bit.exe
solves several problems: