The size limit is for all attachments, your single attachment is too large.
I use this site to reduce my images, it is free, fast, and doesn't set off my virus scanners. Just drag your image to the box and use their default to reduce, and then to download!
https://www.reduceimages.com/
Otherwise, we have help stuff here:
https://www.quiltingboard.com/qb-help-center-f27/