How does it work to sell stuff at bookoff?

Hi! So after moving I've ended up with some stuff i don't want to keep and since there's a giant bookoff about 10min walk from my place I wanna leave it all there, is there anything in specific i need to think about? It's mostly clothes and shoes that are in the laundry right now but also figures and decor.

Is it possible to go any day and do i need some sort of membership or can i just walk in with it and leave it at the counter?

Thanks for the help! ^{^}