Hello @danielludolf !
Is it present, but just "greyed out" / not writeable for you? By default, only Administrators have access to create "Vanity URL"s or "Content URL"s. However, it can be enabled for publishers with the following setting in the /etc/rstudio-connect/rstudio-connect.gcfg file:
[Authorization]
PublishersCanManageVanities = true
We explain this in more detail here: Content Settings - RStudio Connect: User Guide
With the NOTE being the important part for your case. I hope that is helpful and that I am understanding your question properly!