Upload Field option in Modern Events Calendar lets you define limitations over the files that users can upload using the File Field in the Booking Form.
Modern Events Calendar Upload Field Options
In the first field, you can set the file types that you are going to allow your users to be able to upload.
Maximum file size
And in the second field you can set the maximum size of the files that you are going to allow your users to be able to upload. The unit is in Megabytes “MB“.