Are you dealing with downloads that you have purchased or just talking about tryouts?
If you have downloaded purchased Premiere Elements 13 Windows installation files with a serial number, you cannot use those installation files on a Mac computer.
If you want a downloaded purchased Premiere Elements 13 Mac, you need to purchase Premiere Elements 13 Mac with its own serial number for your Macbook.
If your original purchase gave you a box packaging of the product, you found that you had 2 installation disc - one for Windows and one for Mac. In that
case, you could install Premiere Elements 13 Mac on Mac from the Mac installation disc.
Please clarify the details.
From what you wrote, your purchased serial number is for Premiere Elements 13 Windows, so you cannot insert the serial number for the Premiere Elements 13 Windows into the Premiere Elements tryout on Mac. Purchase of the Mac version product with its own serial number is needed.
If you had purchased the program originally in boxed packaging, you would be in a better situation now. As I mentioned previously, that boxed packaging come with
the 2 installation discs, one for Windows and one for Mac. Adobe does not sell the box packaging version, only the download which restricts you to Windows or Mac purchase.
The box packaging can be obtained from authorized resellers.