I have been trying to get Steam to work on my kubuntu installation, but have hit a road block - adding a library on either of my secondary drives gives me a "Failed to add library folder" followed by a "Steam library folder is not executable". I have tried the basic troubleshooting steps - tried to make the drives mount into /mnt/ instead of /media/, adding the "exec" option to my fstab, as well as trying to chown the entire disk. None of these have worked. The permissions tab shows that I am the owner, yet steam refuses to make the folder. I have uncommented the fstab entries and tried mounting the disks to my media folder, and that is where I am sitting now. Any help? These were my /etc/fstab entries:
UUID=E28C-544E /mnt/D exfat defaults,user,uid=1000,exec 0 0
UUID=98D9-3330 /mnt/M exfat defaults,user,uid=1000,exec 0 0
chmodorchowncommands aren't going to have an effect. My guess is that this has to do with an internal Steam problem. Steam may not have been correctly installed and does not have privileges to create a folder. It's not clear from the description what OP is doing, but perhaps they should create the folder using the file manager or terminal, then they can direct Steam to use the existing folder instead of asking the Steam client to create a folder in a location that it has no privilege to do so