As you are developing you are able to see everything you are making, but as soon you want to view something at certain pages you are talking about roles that have access to certain pages or micro flows. First look at what role you are using currently.
The user must have access to the page for this page. If the save button is not a default button, but you added a microflow then you have to give the user access to the microflow also. Also have a check on the entity access for the user what the user is allowed read or read and write etc.
Hope this helps you!
It is possible that the user does not have permissions on Microflow that the button call.