You negotiate the scope of the work and tell them what can and can't be done based on their budget.
You could create something that lets them create their own tables and forms if that's what everything and anything means for you. But I suppose it's something along the lines of building a flexible system. You build those by not hardcoding things that should be dynamic or customizable. So, find out what should be dynamic or customizable first.
You provided a default value to some fields.
If those should be dynamic, that is, if they should be based on something, find out what they depend on.
If those should be customizable, that is, if the users want to change the defaults themselves, then store those defaults in a table and let your user modify them so that those values can be updated on demand, do not hardcode them in the form.