There are 3 main storage options for files submitted on your Formplus forms - Formplus, Google Drive & Dropbox. The storage option for your files is dependent on your preferred storage location. You can see this article to know how to enable storage option on your Formplus account.
You can download files uploaded to your form irrespective of your storage option.
For files stored on Formplus;
Go to the Responses page of your form and click on the file you want to download, you will be redirected to a download page.
Click on the Download File button below the file name at the right side of the page. This will automatically download your files which will be stored in the download section of your file explorer.
For files stored on Google Drive
Locate the file upload folder for the form (you can do this by searching your Google Drive using the form name, this will cause the spreadsheet and file folder for the form to be displayed)
Click on the image you wish to download, select the Download option from the list of options displayed.
For files stored on Dropbox;
Locate the file upload folder for the form and
Click on the image you wish to download, this will redirect you to a page with the full image on display.
Click on the Download button at the top right of the page to download the image.