So you want to add/create an account I assume? The object, when not logged in (so as an anonymous user/session) should be able to be created by an anonymous user. If the object you want to create cannot be created by either anonymous users or users without the proper access rules then it wont work.
If it's an account: make a non persistent entity in a different module (name it AccountCreation or whatveer you want) and let that be created by anonymous users. You can then either use a deeplink to finish it or if you wanna start simple let microflows handle the creation of the account object. It's just a suggestion but I at least believe your current issue lies in my first paragraph.