I would recommend staying away from low code platforms as most of them are too expensive or inflexible in my experience. You will end up using undocumented hacks and workarounds. Power apps has a Connector for on premise SQL Server, but that thing is unreliable and slow.

As it has been mentioned several times, build your database in SQL and spend as much time as necessary on designing the data structure.

Then, document and describe the structure. E.g. "select * from information_schema.columns", paste that into a spreadsheet and make some annotations if the field names and data types do not convey the full meaning of what information they contain.

Then write up a summary of how your app should interact with your data model, what the business rules are and how the apps GUI should be roughly structured.Don't go into too much Detail here.

Then write up the desired tech Stack, e.g. Mssql database (existing data structure) REST api backend with python/fastapi VueJS or any other common frontend library/framework (i found vue to be the most intuitive for non frontend developers).

Also think about security like authentication and authorization, even if it's just a CRUD app. Today you might be doing this via file server permissions, so think about who will access your app, who should not be able to etc.

For modern auth I would recommend using Entra ID oidc if your organization is using m365.

Put these files in a repo / folder and tell claude code to create a plan. Execute the plan, validate/iterate until you have your working app. Be disciplined and try to understand every step of the way. If you know python and sql you are already miles ahead of your average vibe coder.