Another external files question

Hello everyone this is my first post here. I am looking for a definitive answer on how I can transfer files from my op1 to my Android pixel 2.

I have read a plethora of posts all over the net, that tell me this is possible. The ways to do this range from buying a Kingston mobilelite, or similar, to just using an otg cable.

I went with the otg cable route because its cheap and I was able to look into this weekend. Downloaded lots of otg apps for my android phone, including total commander and a USB utility (which was paid for)

The op shows up in total commander however it tells me I can’t move the files.

I’m away soon and want to get this resolved before then, so I’m hoping someone can just say:

Do this xxx

Buy this xxx

And it’ll all work!

Thanks for any help.