Terms can not be shared multiple times in the same term set.
i thought mine was because the Metadata Column wasnt really connected to my Term Store, and that caused that i chose terms existing in the term set yet he didnt find them and tried to recreate them.
all that started cuz i didnt check the Available For Tagging checkbox.
note that he creates teh pages anyway again and again.
then i just deleted the terms i originally put and it worked, but now i am without terms...
so something is just wrong and i'll go find myself a new tutorial
after some extra play i think i got it
if in your navigation settings you set for structural navigation then you get an error: "We could not find the navigation term set for this site. Navigation integration and friendly URLs will not be configured"
so to fix that you need to go back to navigation settings and set the navigation to managed navigation. but there if you choose the term set that the catalog is going to use (cuz its the only one there cuz its a test site for testing the catalog feature) then he "tries" to double set the term set.
eventually i chose on of the OOTB empty TS and connected again and i made it :) !!