Exporting ID CS6 indb to epub crashes, OS 10.13.6 + Kindle Previewer error & can't install New Kindl

Hi, apologies if this has come up but I can't find anything similar to my prehistoric workflow. 

I have a rock solid mid 2012 macbook pro running 10.13.6 (High Sierra) and a duplicate set up on a 27" imac. I am running High Sierra because CS6 is paid for and my early tries at CC failed miserably, maybe because I am off the grid A LOT. 

I rarely do client design work anymore and love my very stable workflow. I need to convert a 208 page textbook in CS6 .indb file to kindle and am running into mega problems. The Kindle export software won't install on 10.13. I can't go to 10.14 becaue of CS6. The epub export is crashing ID. If I take an individual file from the .indb book and save as idml it will save as epub but the Kindle viewer doesn't see a "title" and gives me an error code. I have sent this error to Amazon but haven't heard back. 

Has anyone out there tried to do this with the same set up? Should I bail and hire someone to do this conversion (last resort)? Is there another workflow to get to Kindle I haven't seen?

Thanks so much for any and all advice out there. 

-Marina