No success with nextcloud installation

Nextcloud version (eg, 12.0.5):
Operating system and version (eg, Ubuntu 17.04): raspian
Apache or nginx version (eg, Apache 2.4.25): nginx
PHP version (eg, 7.1): php5

I’ve spent so many hours unsuccessfully bringing nextcloud to my raspberry pi. I can always log in, but do not upload any files to the cloud or install APPs. I’m desperate. It would be nice if someone could help me. I’m ready to pay for it.