Using python script to merge pdfs together.
Install package
pip install pypdf
Script:
from pypdf import PdfWriter
pdfs = ['file1.pdf', 'file2.pdf', 'file3.pdf', 'file4.pdf']
#merger = PdfMerger()
merger = PdfWriter()
for pdf in pdfs:
merger.append(pdf)
merger.write("result.pdf")
merger.close()