Chavapulco

Hi, I’m new to the forums and kind of new to Ark in general starting playing ASE summer of last year. But with ASA, on PC now. How can I transfer my resources and junk to my mount, while mounted? I thought maybe it wasn’t a feature anymore, but while watching streamers on YouTube they can transfer items while in flight like on their argy. I tried looking in settings but I gave up even on Google search. I’m sure it’s simple but I’m too noobish to figure it out. Please help, thank you in advance