BILILI comics

you can't use your avatar? or the card that you obtain doesn't work/appear?

I think the whole Avatar/ Card system is just for fun. While reading chapters you get random cards to dress you avatar, so the more chapters you read, the more cards you get.
Also you can fuse or destroy cards, you don't need or want, to either get a new card or fragments (you need these to fuse cards).

I think Once I understood the card system with clothes, i can change clothes. But no one else sees our avatar if I understand correctly, and there is no interaction between avatars..

I think that too, but I find it a shame because even if you have S cards afterwards you can't even merge them, throw them away or make an exchange with another player