Export Media Creating Movie stops at 99%

I would keep them individual files, export individual videos, and stitch them together in Premiere Pro.

i don't understand this, "I have an 11 minute file consisting of four subfiles

One of the files is 7 minutes long, so I added the three other files to it, using scenes."

do you mean you have 4 video files that you're trying to combine?  if so, premiere is a better tool for the job, Combine multiple video clips in a single sequence | Adobe Premiere Pro tutorials

animate could be used but you'd need to keep your main timeline under 16,000 frames. at 30 fps, an 11 min project could exceed that.  at 24 fps, you'd just make it under the limit, but even that may not work.

and your gpu performance is a significant determinate to ame rendering speed.