Using Free profile can I create a User that use My App without permission for edit it ?
Yes, you should be able to put users in groups and then for that group under Apps, select "Use" only. Under settings (click on your avatar on top right when in Retool), create a group, add the users, then select Permissions. then the group you just created and go from there.
I have now learned that with Free Profile I cannot create custom groups so i cannot assign user to a group with sort of permissions. It is not so ?
That’s correct! User permissions start on the Business plan.
Here’s a doc on user permissions in case it’s helpful for you 
This is rediculous. Are you saying that any user of any app needs write access to the production database unless you are on Business plan or higher. What is the point of the lower plans?!
Just signed up to one but will obviously need to cancel since it's useless without this possibility.