Communicate with nextcloud

i installed nextcloud with an virtual box.
and i can set files in my nextcloud but i can’t see my files on the nextcloud app in my phone.
i searched a lot for solve that problem but i can’t find a solution.
can you help me please?

It could be that the file names are cached. Normally you can pull the list up to reload it… For more details, please move to the correct client-category (android/ios/…) and provide more info (does logfiles show error on your server).