Thread:User talk:Rua/Lua error in Module:auto cat at line 503: This template/module can only be used on pages in the Category: namespace.

Hello, I have seen on the talk page for 'PulauKakatua19' that you recommend to him to use 'autocat' to create a category. I didn't know about this, should 'autocat' always be used? Thank you in advance.