Create PHP Application for Information Transfer of Invoices

We need an object orientated PHP Application, which will run on a single Ubuntu VPS. The Task, which can be executed by cron will be:

1.) Downloading Invoiceinformation from an API
2.) Check, which of those Invoices have already been processed by the Application (Save Invoice ID‘s to Database)
3.) Download the PDF‘s of the not processed invoices
4.) Convert the Information from the not processed invoices to a XML Format
5.) Add the PDF Invoices to the XML by referencing the filename in the XML File
6.) Create a header.xml File which contains information about all the single XML Files for each invoice and the PDF‘s
7.) Zip everything together to a package

Important is, that the Data from the invoices that need to be processed will need to be converted. On each Invoice Line there is a unique service identifier, which matches a cost category for example.

The main Task is to download Invoices from a API, convert them to a Format, which is compatible with our Bookkeeping Software.