Unable to transfer photo and video

Hi , just got my Sandisk IXpand 64GB 3.0 , but from 1300 something file I just got 61 transfer. I try to turn off the Icloud already , but not help. Trying to turn off mu photo in Icloud , Iphone ask me to free my storage first which is hard for me to give up my video. And the first time I’m download the sandisk app , I’m accidentally press NO in term when Sandisk ask me to share my file ( is that the problem for me ? ). Please help since I’m newbie with technology like this ??? . And Thanks in advance ???