Publishing on platform for storage purpose will only be available without the BI Addon on version 1.22 of Lumira (latest available version is 1.21).
See this comment from Sharon Orn :
In 1.22 you can publish the lums file itself to BI 4 for the purpose of maintaining in the CMS repository and securely sharing the whole document. This workflow can be done directly to BI 4 without the need of Lumra Server/HANA, Lumra add-on, but in order to view the content of the lums file, you need Lumira Desktop. When you click on the Lumra document from BI launch pad, t will try to load in Lumra Desktop. Hope this makes sense. Please let me know if this is not clear.