I have an Acer C720 Chromebook and as I understand it, once you've created an initial document and edited it to whatever format you require, you can then save it as a PDF (or any other available extension) downloading and using it accordingly for whatever reason you need...
Should you need to edit the said PDF, simply go back to the original (which will have been saved automatically at the default extension) revamp the document and again ~ save it as a PDF, leaving it with the same name (thus overwriting the original document) or creating a new name should you wish to save that original...
Haven't had time to experiment to any length or depth, but briefly: that is what I've managed to achieve....
Hope such might be helpful...
Robbie....
Should you need to edit the said PDF, simply go back to the original (which will have been saved automatically at the default extension) revamp the document and again ~ save it as a PDF, leaving it with the same name (thus overwriting the original document) or creating a new name should you wish to save that original...
Haven't had time to experiment to any length or depth, but briefly: that is what I've managed to achieve....
Hope such might be helpful...
Robbie....