You need to resolve your dependencies conflict defined composer.json.

First, read carefully what error stack trace says. The issue is not only with clickandmortar/import-bundle but with doctrine/orm as well, require (^3.3), - what is your current definition for that package in composer.json ?

Second, follow what composer advices itself run your command with argument -W php require league/csv --with-all-dependencies , - it will try to resolve conflicts automatically.

Third, you will possibly need to delete composer.lock file (don't forget to backup) as it can have issues.