Hi @nextend_ramona,
I have not checked Shop manager roles and permissions and it is possible, that he/she does not have access to Smart slider settings by default and only the Admin role can see the whole package. Your amazing and well-detailed explanation helped great and my user with the Shop manager role can see the Smart slider and is able to create and update slider now. Thanks a lot. I used User Role Editor plugin in the past, when working on another project, but assumed that Adminize will do the same trick as URE and I did not want to use more plugins than is necessary. I think your answer will also benefit the whole community. Thank you again 🙂