I'm using jot form, but the maximum upload only says 1024kb which is not useful. Do I have to pay additional for customers to upload larger files?

website is ponds-waterfalls.com

The maximum file upload size can indeed be increased, you do not need a subscription to do so.  Here is our quick guide detailing how to increase the limit as well as the maximum file sizes for different integrations:

https://www.jotform.com/help/33-Changing-the-Upload-Size-Limit

You can also change the allowed file types:

https://www.jotform.com/help/29-Upload-Field-Allowed-File-Types