Files

@formField('files', [
    'name' => 'single_file',
    'label' => 'Single file',
    'note' => 'Add one file (per language)'
])

@formField('files', [
    'name' => 'files',
    'label' => 'Files',
    'max' => 4,
])

Option	Description	Type/values	Default value
name	Name of the field	string
label	Label of the field	string
itemLabel	Label used for the Add button	string
max	Max number of attached items	integer	1
fieldNote	Hint message displayed above the field	string
note	Hint message displayed in the field	string
buttonOnTop	Displays the Add button above the files	true false	false

Similar to the media formField, to make the file field work, you have to include the HasFiles trait in your module's Model, and include HandleFiles trait in your module's Repository. At last, add the filesParams configuration array in your model.

public $filesParams = ['file_role', ...]; // a list of file roles

Learn more at Model, Repository.

If you are using the file formField in a block, you have to define the files key in config/twill.php. Add it under block_editor key and at the same level as crops key:

return [
    'block_editor' => [
        'crops' => [
            ...
        ],
        'files' => ['file_role1', 'file_role2', ...]
    ]

No migration is needed to save files form fields.