I need help with my first home server. Permission/ownership and samba issues.

I have been using linux for a couple of years already, very casually, just browser, media, games. Recently I bought dell micro pc and installed proxmox on it. I don’t have a lot of hdds or raid or anything, just one 6tb usb external drive. I know, I could lose everything, but I don’t have anything important in there, just...