Hi,
The following link is instructions installations in QNAP and SYNOLOGY for web server with PHP and MySql.
Now to install Dolibarr will need to download the latest version from here the zip or tgz.
After you download the file and unzip it you will find the htdocs folder will transfer the files inside the htdocs folder in the folder you created on your QNAP or SYNOLOGY.
After you open the browser you are using and the url will put the corresponding url that you created in one of two NAS and follow installation instructions dolibarr.
Kind regards!
Nikos