Do I need to join any Clan?

If you ever run out of challenge options in the map that rewards the craft materials, you should know that joining a clan and asking your clan members for these resources is one way to get them. However, obtaining resources through this channel means you'll have to repay it some way sooner or later. That is mostly the benefit of being in any clan in the game.

If this is particularly your problem, you should go ahead and join an active clan. Alternatively though, if you happen to have a lot of (unused) artifacts in your inventory, those old and weaker ones that you do not need anymore, you have the option to disassemble them and get some surplus raw materials from it. Use the “Dissipate” option when you view an artifact in the statue.