Yes, the default map is only for testing/features preview.
For a real map, join the Discord and check the release/map channels. There is already a Crystal 15.25 global map downgraded to 8.60 clientID.
Check out the forgottenserver-downgrade-1.8-8.60 community on Discord - hang out with 212 other members and enjoy free voice and text chat.
discord.gg
If your map uses serverID, convert it to clientID with NexaMap Editor first.
Also check config.lua: default NPC mode is "tfs".
For Crystal/Canary NPCs, change it to "crystal".
NPCs and monsters are already ported/configured for 15.25.