How do I make a custom user interface of tables?

I am looking to do something like this. Any ideas or advice?

All of this can be handled in UMG quite easily. Use horizontal and vertical boxes to create table like elements. Otherwise, it looks pretty straight forward to do in UMG. The tabs on the left can be either buttons that turn on/off visibility to elements within the same UMG widget, or can be a separate widget that can bring up other widgets. There are some good tutorials to get you started here: UMG UI Designer | Unreal Engine Documentation
Does this help?

For the most part yes. The top boxes labelled Unit, Class, Exp Level, Dropships, Upkeep are the column labels of a generated list that changes depending on the location. There might be 1 Unit in one place and 5 units in another. In PHP it was easy to create a flexible table that boxed each variable. In UMG I can create the list in a multi-lined box but I still need it to only have the rows that have variables appear in boxes.

I think I understand what you are saying. You have the same number of columns for each row, but there could be a variable amount of rows, correct? I built something like this using datatables for a conversation system that I was working on awhile back, and I basically laid out all of the places that the dialog could be ahead of time and then dynamically changed what dialog went on which textbox based on user control input. I don’t think that would work in your case, however, as it looks like you have categories and sub-categories, all of which could be dynamic. I don’t have a ton of experience doing what you are asking, but I did come across this that might be a direction to look at: Creating Widgets | Unreal Engine Documentation
Specifically the section about adding widgets as a child of another widget. Perhaps you could create separate widgets that you dynamically add to a main widget on runtime or something like that. Sorry I can’t be more help.