Could you be a bit more specific what your problem is? For example which container you are using and where exactly you run into trouble configuring it?

Thanks for making that clear! 

For now I get basic functionality for online reading and navigating via nextcloud & it's epub/cbr reader plugin. Not anywhere near a dedicated reading platform with metadata and covers but usable and quite fast. Versatility (like having audiobooks on the same platform) is a plus too. 

Best of luck with your project! 

Sorry to hear that. Guess I have to stay with Ubooquity then. The curse of large book collections. I think I'll manage somehow...

No problem, I'll admit it may be an edge case having to somehow manage such a large amount of books... I wonder if there might be a way to stramline automatic editing of the metadata. Somthing akin to Tag&Rename fpr mp3 metadata. As long as there is no good way to pull Author, Title and Series data from filenames and folders I see no viable way to reorder my collection except using folders...

The missing folder view makes it impossible to use for me too. My ebook collection has thousands of titles which are partly sorted by author, and partly by franchises (Trek, Warhammer, etc.). In Kavita its totally scrambled and not navigable at all.

Komga looks and works really! good, but unfortunately until it supports reading actual text epubs its of very limited use to me...

Please take a closer look at the PGID and PUID variables of the linuxserverio image (refer to "User / Group Identifiers" in the
instructions). You want these to reflect your syno's dockeruser IDs to avoid using su rights. You can get them via SSH. For my DS its PUID 1031 and PGID 100.

Perhaps consider using a docker image liike linuxserver/ubooquity:latest for a really effortless installation and maintenance...

Usually you would not need to use this repository at all, since the docker app is part of the official synology app suite and can be installed and managed quite easily from within the DSM package manager.

Aside from that, I think the source of your issues is your containers configuration. Make sure you have mapped the required folders correctly, applied the necessary access rights to these folders so that docker can actually access them and provide the recommended environment variables and port allocations. The linuxserver/ubooquity docker actually makes a very good job in providing the relevant instructions on the page I linked.

Try pulling the linuxserver/ubooquity directly from within synology's docker app.

(https://hub.docker.com/r/linuxserver/ubooquity/)

The directory you listed contains synology's docker versions. You should not need these normally. You can manage everything from within the DSM.