Hi @manuel and thanks for the question.
To be honest this is not a question that comes up very often so the answer may not be ideal. Our version of Balsamiq for Confluence is tightly integrated with Cloud - especially from a user access point of view - so there’s no feature built into the integration to allow your wireframes projects to be shared with users outside your Confluence instance.
If it’s just a single wireframe you wish to share, you could use the Image Link feature.
The most practical solution would be to export the project to an interactive PDF file and share that with your viewers. See: Exporting to PDF
This has the advantage of keeping all your wireframes in a single file and offers the additional benefits of working links and selectable text.
Finally, and there are definitely limitations to this suggestion, you could download the .BMPR project file (it’s just an attachment to the Confluence page) and share that with your users. They can download our desktop app - Balsamiq Wireframes for Desktop - and use that to view the project. The desktop app comes with a free, 30 day trial but, even after that expires, they can continue to use the app to view project files. It’s not ideal btu maybe you can make that work for you and your external users?