import fitz
import pdfplumber
my_path = r"C:\Users\DELL\Downloads\A-24VU-00511.PDF.pdf"

with fitz.open(my_path) as doc:
    order_numbers = []
    order_dates = []
    buyers = []

    for page in doc:
        text = page.get_text("text")

        if "Your ref. no. PO" in text:
            parts = text.split("Your ref. no. PO") 
            for part in parts[1:]: #idziemy od 2 elementu, żeby nie brać tekstu
                order_number = part.split()[0].strip()
                order_numbers.append(order_number)
        
                   
print("Reference numbers: ", order_numbers)