Docker jDownloader

Hello guys,
first of all, sorry for my english, im just a german student

Second, im a newbie in linux, but i wanna learn sth.
So i set up my first NAS yesterday with a raspberry 3 b+ and a 4tb wd red.

I installed OMV 4 and docker. With some tutorials and googling, i managed to get the plusminus jdownloader headless image to docker.
i tried to set it up step by step as @RPMan told it here but i''m doing sth wrong

When i launch the container i got the error message standard_init_linux.go:207: exec user process caused "exec format error" but i dont now how to handle that one, sry

ok thx for your help guys, now the container run, but i cant configure it

i tried to execute docker exec jdownloader configure email@email.com password via ssh, but i get the error

cp: can't create '/opt/JDownloader/cfg/org.jdownloader.api.myjdownloader.MyJDownloaderSettings.json': Read-only file system
sed: /opt/JDownloader/cfg/org.jdownloader.api.myjdownloader.MyJDownloaderSettings.json: No such file or directory

how could it be, that the config folder is read only, when the container creates like 20 files there?
what do i need to change? the system is fresh set up, i dont set up some users, just one for ftp with full access to the whole NAS storage

Yes i use openmediavault-docker-gui 4.1.3.

ok ehm that was my fault, i dont know why, but whilst setting up i put the checkmark on read only ... my dumb

now everything looks like working, thank you for ur help