Create a Form in confluence to request new access or new user

Hey @Dario, here is an alternative to Nic's answer: if you are already using Jira and want to have a Jira issue in the end, have you considered using Jira Service Desk instead for such kind of requests? You could provide your own interface of fields and your JSD request is backed by a Jira issue (it actually is a Jira issue).

Confluence is more aimed at free-form text and documentation, not entering "forms" or running process flows.  Jira is more form-driven as it has custom fields and is based on a workflow engine.

If you're going to to this in Confluence, you will need an add-on that provides forms.  It's worth looking through the higher entries on https://marketplace.atlassian.com/search?product=confluence&query=form

In the interests of openness, I work for one of the vendors of the one of the most popular options, but I'll stay away from a direct recommendation because I don't want to appear biased, and I don't have much of your requirements or an idea of how you'd like it to work.