A board can have up to 50 custom fields defined on a board. Any number of cards on the board can have values set for each field.
How do I get past this 50 custom fields limit? Other than creating multiple custom fields for the same type of item.
You could try out the Amazing Fields powerup. I don't know if it would meet your field needs, but I know many people have more than 50 fields with it. The maximum you can have depends upon the complexity of your configuration but I have created some boards with simple text fields with over 300 fields.