Video iPhone15/BMCloud

I have 120 gigs of performance video on my iPhone15 Using Blackmagic camera app. Unfortunately, I chose to keep video with BMC app. I cannot get it off my iPhone onto a drive and the only way I have discovered with a tech at a MacClinic is to send it to my Blackmagic Cloud account. I have 2 gigs free. But I need 120 gigs, No matter how hard I try to upgrade my cloud account, the screen goes blank. Any button that I think will to take me to upgrade goes white or black. This is making me nervous. I've have to screen the video in a week.
Any advice??? Who to ask?
Any advice??? Who to ask?