EDIT: just noticed that the used image is for x86-64 and not for arm, so you need to check if there is an arm image for the RPi and adjust accordingly.
I use this docker-compose file
You can run it in portainer
After the docker is up, you can reach filezilla from the browser
I was able to successfully install portainer, but I don't fully understand your instructions. Is there even an arm version for Filezilla? I can't find any. Or does portainer make jlesage/filzilla which is amd64 somehow work?