Application for Driver's License exchange

This is going to be hard to figure out over the internet.  If you can possibly enlist the help of someone who's familiar with your situation and your computer setup - it wouldn't have to be on site, if you can reliably send documents back and forth via email or something.  The process of getting all these documents into readable submission form within the size limits and everything is somewhat exacting.

It isn't clear but it sounds like in the driving record case, you have run into the web form size limit - you can't submit the file, because it's too big.  In this case, you have to make it smaller.  If you were using MacOS, for example, you could use Preview - but only with an image file, e.g. JPEG format, if I remember right.  So you have to get all the images out of the multipage PDF document into JPEG image files, reduce them by the amount you have calculated is necessary, and reassemble a new PDF document.  Or you can go back to the scanner and get lower resolution scans.  That may not only be a confusing explanation, it may have nothing to do with where your problem is ... welcome to the internet.

You should also note that any stamps the consulate made on your materials, have to be included - e.g., there should be a photocopies of the foreign drivers license, and somewhere on that page is the consulate's stamp.  All must be present.

And don't neglect the statement from Finanças that you live in Portugal.  Some lists of required items don't mention it, and there isn't a place on the form to submit it;  you can just put it under additional documents.

You should preferably use the PDF format. Use websites to compress documents in PDF, JPEG..., (high compression without loss of quality) ... there are a lot and free available on the net.

If JPEG format, then convert to PDF format

I got the same problem even by trying a lot

every time a document was not correct but no more justification

I kept all the évidence about the correspondancy with the IMT, just in case

Then I give up