Around that version (3.5 or 6) I think there was still a question upgrade helper which was introduced in 2.x.
References:
https://docs.moodle.org/2x/pl/Question_engine_upgrade_helper
https://docs.moodle.org/dev/Moodle_2.1_release_notes/New_question_engine
If you un-archive the .mbz file (the backup file) in the resulting unarchive look for a moodle_backup.xml - that should tell you what moodle version the course backup came from. And there is a questions.xml file. That also might give you some clues.
There is this discussion from many years ago:
https://moodle.org/mod/forum/discuss.php?d=381494
If you really want to use it, you might have to edit questions.xml and strip out offending tags.
The more info link
https://docs.moodle.org/404/en/error/debug/codingerror
Said this:
This question is of a type that is not installed on your system. No processing is possible.
This is caused because you are attempting to see/use a Quiz that uses (at least) one question that has its status as 'Draft', not ready. Change the status of the question (in the Question bank) to 'Ready' to fix this.
If you do edit the questions.xml file to give it another try, you will have to repackage the .mbz file from inside the unarchived .mbz to get it to uncompress as moodle would expect it to uncompress.
Fun and Games!
Good luck!
'SoS', Ken