I´m just posting this info as there seems to be regular requests and too much disinformation and crappy browser addons/extension. This sexy little python script seems to be the only free tool which currently works and does get the full caption. It is so far on active development via github.
If you already havy python3 installed, all you need to do is
downloads public and private profiles, hashtags, user stories and feeds,
downloads comments, geotags and captions of each post,
automatically detects profile name changes and renames the target directory accordingly,
allows fine-grained customization of filters and where to store downloaded media.
I know it may be useless to say, but try no to get into MASS-BATCH-HELLYEAH frenzy mode, so we can all continue to enjoy the beauty and simplicity of this piece of code at least for a while.
So far, I have downloaded 1000-2000 download batches twice a day for each profile and IP for a few days with no problems at all.