The file size limit in the conference room is 100MB. If you're file is larger than that, you may have issues uploading or presenting it. We recommend compressing the file. We also recommend saving PPTs has PDFs as the room will convert any file to this format. If you PDF file needs to be compressed, you can do so for free here.
You can also use the BigMarker PowerPoint Uploader, which helps with uploading and formatting.
If you continue to have issues, you can also share the PowerPoint application through screen sharing.