Basically your problem space resolves to 3, possibly 4, steps:
- Receiving the order - I am guessing this might be an email.
- Extracting the correct data from the PDF if it is in that format
- Extracting the correct data from a webpage format if that
- Inserting the extracted data into the excel worksheet
The tools that I would use to work through this in the Python world.
Getting the "Order" files
Since you aren't specifying how you are getting the orders I will assume that they are coming by email, python has a number of email clients available including a built in email module, examples of how to interact with mail servers abound. However, since you are manifestly getting the data somehow I will leave how to automate that to another question.
Extract from PDF
Within the Python ecosystem there are a number of pdf manipulation tools but probably the best fit for this is PDFMiner.Six which specialises in text extraction including the exact location of texts in a page. An example of using PDFMiner can be found on SO here.
Extract from Webpage, (HTML)
Just about everybody in the python world who needs to parse html data turns to BeautifulSoup4 which can parse just about any web page, (even badly formed ones), to extract the data. Presumably the data that you need to extract are in named fields within the page - if so you will find that they are easy to extract.
Insert into Excel
Depending on whether you need the Excel 2010 XLSX files or Excel 97/2000/XP/2003 compatible XLS files you will find the tools that you need to crate & manipulate excel files in either openpyxl or, for the older file format, XLWT/XLRD/XLUTIL.
One of the nice things about these is that they do not require a copy of Excel to create or manipulate the contents of excel files.
Price & Availability
All of the above tools are free, gratis & open source, and are cross platform so can be installed on just about anything from a Raspberry Pi to a supercomputer cluster, even on MS Windows.