Failed to create folder root directory mkdir

Hello! I am trying to configure Syncthing on my local openmediavault server. However when I try to create a new folder in the GUI where I want future files to be synced to, it says: Failed to create folder root directory mkdir. The interesting is, that when I check the env of the container, GUID is set to 998 which according to this command:

awk -v val=988 -F “:” ‘$3==val{print $1}’ /etc/passwd

is not even a user. When I try to change PUID and PGID to some different values for example to 998 and 995 according to the: id admin command the serverip:8384 is not even accessable. Ids of root is working though but I’m not sure that it is safe. I’m really new to this Linux enviroment so sorry for not understanding completely.