Switch for creation and editing of a single CPT by a user

Tell us what you are trying to do?
I want to give the user the option to create only one CPT (Custom Post Type) post. For this purpose, I am using the submission form with a connection to this post: https://toolset.com/forums/topic/limit-post-count-per-subscriber-to-1-post-forever/#post-266572. Once the user has created this post and clicks on the "Create post" button again, they should be able to see and edit their already created post. I am aware that I could solve this with two separate forms, but that would mean I have to maintain both separately whenever there's a change. Is there a way to achieve this using a single form, with a switch such as if the user has already created a post (post count > 0), show the edit form with their post, otherwise show the creation form?
Is there any documentation that you are following?
https://toolset.com/forums/topic/limit-post-count-per-subscriber-to-1-post-forever/#post-266572
Is there a similar example that we can see?
Not that I am aware of.
What is the link to your site?
https://business-websolutions.com
The website is currently under construction, and to perform a more in-depth inspection, I would need to create a new user first.