Quantify for Bitbucket has no access to the source code and will never ever request such. We need only metadata such as authors, commit messages, branch names, etc.
In order to connect Quantify Jira addon with Quantify for Bitbucket, you need to do a couple of steps.
Make sure you have installed the Quantify Jira addon
Install the app by following https://marketplace.atlassian.com/apps/1220113/quantify-for-bitbucket
Make sure you install it on behalf of the team and not an individual account
After the Bitbucket addon installation, you will be redirected to this page
IMPORTANT: Connect your Jira in Bitbucket settings
You will be redirected to provided Jira host where you will confirm the connection.
All done! You can disconnect anytime