Exporting photos for large printing

Hi, I have a total noob question. I would like to create a photo album that's 12x14. So the photos will be quite large. I have all the raw photos that I uploaded into Lightroom, made the edits and then exported them in JPG so that I could upload them to Snapfish to make the photo album. The problem that I'm running into is that Snapfish recommends that the image mb size be around 10mb or more especially for large images. A ton of my exported images are 4-5mb, even though the original raw files are around 20-50mb.

I don't want to put together a whole album and pay hundreds of dollars only to receive an album that looks terrible. Yet, when I go to export the images, I select JPG and highest quality, and that's the file size I get. So what's going on here? Am I missing something? Is there some setting that I'm missing? Or am I ok with using those JPGs and everything will be fine?

Also, Snapfish has some really good rates on albums this month, but I would like to get a really high quality photo album. Are they the best company to go with, or are there better ones?

I have a cloud based lightroom 8.0 on windows 11