Hi @Bjorn
I saw that you posted the same question twice on Q&A using 'Excel' tags. I can understand your feeling.
But the 'Excel' tag focuses on general Excel usage issues.
Via searching online, I find the link: https://learn.microsoft.com/en-us/partner-center/marketplace/submit-to-appsource-via-partner-center
I suggest you post a new thread on the community that mentioned as following image.
There are also some additional instructions for uploading add-ins listed on the left.
Hope the information could be helpful to you.
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