Assuming you know the paper size and the scale the architect has set (eg: 1:100) you can use the steps below:
- Download the file below that corresponds to the paper size of the plan you're stuck on
- Load it into the "Plans & takeoffs" section with the other page(s).
- Hit the "Scale" button and select to "Scale all pages"
- Choose the page uploaded in Step 1 as the basis of your scaling
NOTE: we make more of these files on request, so if there is a page size we don't have let us know