Width comes first
Image dimensions are normally written as width × height. Reversing them turns a portrait box into a landscape box, so copy them in the same order shown by the portal.
Why cropping is better than stretching
If your photo and the target box have different shapes, simply forcing the image into that box distorts it. A center crop trims the edges while keeping faces and objects proportional.
Pixels are not file size
Two images can both be 200 × 230 px but have different KB sizes. Detail, format, and compression affect bytes. Treat dimensions and file size as separate rules that the final file must pass together.