Yes, I know and I don’t use it. I start my containers from the command line.
Try ssh’ing in to your Synology (which model is it, btw?) and running this command
docker run -d --name=calibre-web \
-p 8083:8083 \
-e PUID=1024 \
-e PGID=101 \
-e TZ=Europe/London \
-e DOCKER_MODS=linuxserver/calibre-web:calibre \
-e OAUTHLIB_RELAX_TOKEN_SCOPE=1 \
-v /volume1/docker/calibreweb:/config \
-v /volume1/web/books:/books \
--restart always \
You’ll have to change the paths to match your setup. Just tried it on my DS918+ and it worked.