PDF Forms on iPad

Hi, I have monthly subscription Adobe and been using on my two MAC desktops. I have iPad Pro and installed the Acrobat. I pulled the fillable PDF file from iCloud on to my iPad. Once I started to fill in the form (PDF), it won't let me save back to iPad or to any folder. I signed in with my credential of Adobe, but the PDF says its Read Only. Also, it asks for password and not sure which password it is asking. The fillable form is not password protected. However, my iPAD is logged in as Apple ID user name. Can anyone assist what could be wrong? Thank you in advance.