Can not edit a Word document

I have a cover letter that I am trying to edit. The letter is in Word format and has several portions where I can enter and replace information for the specific job I am applying for. I paid for the subscription to Premium so that I could edit Word documents and save to PDF format. However, despite numerous attempts, I can not edit the cover letter. I keep getting a message that sends me back to the subscribe to premium acrobat page and tells me that I am already a subscriber. Can somebody please offer some guidance? I have saved the file on my iPad but does not allow me to make any changes.

Thank you in advance,

Kevin