Jira DVCS connector: "Webhook not installed" when adding new repository

We use a self-hosted Atlassian Jira (v7.3) and a self-hosted Gitlab instance (v13.11).
I connected both with Jira’s DVCS account settings (after working around the scope=repo bug) and get the Gitlab repositories listed in Jira.

Whenever a new repository is created in Gitlab, I go to Jira’s DVCS account list and click “…” → “Refresh repositories”.
The new repository shows up now, but a yellow warning icon is shown:

Webhook not installed.

We couldn’t add the post commit hook because you don’t have admin permission on the repo. You can send the URL below to your Bitbucket admin for this account.

The Bitbucket admin can use the URL to add the hook. For more information, see Webhook instructions

https://jira.company.com/rest/bitbucket/1.0/repository/2/sync

In Gitlab’s repositories, no webhooks get registered.
The gitlab user has maintainer rights, which is enough to setup webhooks.
Commits show up in Jira after some time or a manual sync.

What can I do to fix this problem?

Hi @cweiske
AFAIK GitLab is not using the post-commit webhooks. Data are synced by Jira every 60 minutes.