Why are fields that I've marked as 'required' able to be skipped during form completion?

I've exported a pdf from Word into Pro DC. Scanned doc for fields. I edited the fields as needed - required, format, position, etc. Saved the document as pdf. Opened the pdf in Dropbox / File Explorer. Doc looked great, but it's allowing me to skip over the fields that I've marked as 'required.' In DC, the fields are showing in red - indicating that they are required.

I feel like I'm missing a step in the final steps. I hope someone can help me with this pretty simple question!

Thanks!

Ollie