If you want to send a PDF file to Handyman Mobile, you can press "Share" directly in the app where you have the PDF file. If the app doesn't have a "Share" function, you can navigate to the folder on your phone where the PDF file is located and send it to Handyman Mobile from there.
Here are some screenshots of this process:
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You will then be taken directly to the orders and can assign the PDF file to the appropriate order.