It's very likely that installing SatisMeter on your website or app requires to do some changes in code, and sometimes the person designing the survey is not the most adequate to do it.
For those cases, you can share your project's installation instructions with anyone, without the need to add that person as a project member.
The only thing you have to do is go to the survey designer by editing one of your surveys or by clicking on "New Survey". Then click on "Share with my developer" on the top-right corner of the installation instructions. You'll see a dialog with a link in it which you can copy and share with anyone you want.
The link gives read-only access to the instructions. Non-members opening this link will only be able to see the instructions and check if the installation was correct. They won't have access to modify surveys, see responses, or any other SatisMeter feature on your project.