Here are log files for six scenarios. Only two are downloading the subtitle in the movie folder.
downloaded next to the movie --
https://paste.kodi.tv/awopekulog.kodi --autosubs addon enabled, automatically download first subtitle enabled, Play next video automatically disabled, navigate on episode and play
downloaded next to the movie --
https://paste.kodi.tv/osuzaxonod.kodi --autosubs addon disabled, automatically download first subtitle disabled, Play next video automatically disabled, navigate on episode and play, subtitle menu, download subtitle
downloaded to temp ------------
https://paste.kodi.tv/xatowezawo.kodi --autosubs addon enabled, automatically download first subtitle enabled, Play next video automatically enabled, navigate on episode and play
downloaded to temp ------------
https://paste.kodi.tv/ahazuvoref.kodi --autosubs addon disabled, automatically download first subtitle disabled, Play next video automatically enabled, navigate on episode and play, subtitle menu, download subtitle
downloaded to temp ------------
https://paste.kodi.tv/deravutebu.kodi --autosubs addon enabled, automatically download first subtitle enabled, Play next video automatically disabled, navigate on episode and context menu play from here
downloaded to temp ------------
https://paste.kodi.tv/fexicesixa.kodi --autosubs addon disabled, automatically download first subtitle disabled, Play next video automatically disabled, navigate on episode and context menu play from here, subtitle menu, download subtitle