You need to use TYPE or MOD_PLATFORM set to "AUTO_CURSEFORGE" if you want to make use of CF_PAGE_URL. The logs you provided confirm that you're using just Forge. So with your Forge usage you have a typo in the variable name that should be MODPACK: MODPAKC: /modpacks/better.zip...
Both CurseForge and Modrinth gives the same following crash report Had to put it in a google docs as it exceeded the character... Minecraft Mod Server does not start? in Windows 10 Gaming Minecraft Mod Server does not start?: When I try to start a Minecraft Mod Server on my Windows ...