Are you on the free plan? This is from a post with similar question
Each account is allocated one private space, with up to 10 members (including the workspace admin, i.e. the instructor) and 25 projects . You can submit a request to the RStudio Cloud team for more capacity if you hit one of these space limits, and we will do our best to accommodate you. You do need to put in a request for an increase in members for each workspace. If you are using a Professional shinyapps.io account, you will not encounter these space limits.