JotForm provides a web-based form submission tool with some pretty great functionality for the price. 

After you create a JotForm account you should be in your My Forms section. Go ahead and click Create Form and use their drag and drop interface to build your form as you like.

After you're done editing the form, click the Settings>>Emails option at the top:

Now we can add the submission option. Click + and choose the Notification Email option:

Set the email subject to the FormID=## you grabbed from the form category in Workhub:

You can see that I've also added a few variables which you'll find if you click the pencil icon to the right.

Next, choose the Recipients tab and set [email protected] in the Recipient Emails section:

Next select the Advanced tab and ensure that the send uploads as attachment option is set to no, and the pdf attachment option is set to yes. The rest of the options are up to you:

Note that if you don't want to send the submission as a PDF Attachment, it will be converted to an .htm file which will open in the browser. Most users prefer PDF but the choice is yours.

Lastly, to give your workers access to the form directly from Workhub head to the Publish>Quick Share options in the menu and take the URL provided and paste it into the form details page within Workhub: