Your PDF does indeed have fields. It seems to be working perfectly for me in my own WP instance. However, there appear to be a few other issues going on your screenshots.
First, there is the “Cannot access attachment file” error. I’m not sure what is causing it. It may be caused by another plugin. Can you share a list of your currently installed plugins?
Second, it is possible that you may be using an optimization plugin (like Imagify or ShortPixel Image Optimizer). These kinds of plugins might be stripping the form fields out of your PDF (to reduce its size). This will obviously cause problems because my plugin would think that there are no fields in your PDF.
If you can provide a list of your installed plugins, that may give me some clue regarding what might be causing your issues.
Alternatively, if you don’t mind allowing me temporary access to your wp-admin dashboard, please send me temporary login information to my email (admin at maximum dot software). I would be happy to log in and debug the issue for you.