I can’t modify a purchased PDF on premium mobile

I am NO acrobat expert. I work at a daycare and use it to print out coloring pages, name tags, and other craft type pages. A few months ago, I purchased a pdf from teachers pay teachers and used it and edited it and printed from it.

A few days ago I made another purchase, a larger file that came zipped. My iphone unzips it fine and opens it in my premium adobe and then says file can't be modified.. I contacted teachers pay teachers support and they say it's working fine on their end and I NEED to open it from a desktop computer, and they will refund my money but the policy is that they don't so next time you're SOL. 
so I made another purchase hoping it would work and it doesn't- what's going on??