What is the license?
Free to use for a commercial project or whatever you like to do
So is it CC0 (public domain)?
Is (CC BY "This license lets others distribute, remix, adapt, and build upon your work, even commercially, as long as they credit you for the original creation. ")
In this case, you should add the license into metadata for the asset pack(s):
"Edit asset pack->Metadata->Release Info->License for assets" It will increase the size of audience that will be able to find your art
