Help. Installed syncloud on raspberry pi can't upload. Permission denied

I installed syncloud on my raspberry pi 3 and activated my device. Then added the nextcloud app on the raspberry pi.
But when I try and upload anything from the android app I get “You do not have permission to upload in this folder”

I’m not the most computer literate person but I can follow directions

https://docs.nextcloud.com/server/9.0/admin_manual/installation/installation_wizard.html#strong-perms-label