In case you haven't figured it out already, Instagram for Android requires 'both' Android 2.2+ AND OpenGL ES 2.0 support which unfortunately, the Transform doesn't have
This is the reason why your device isn't compatible.
I wonder, however, if you could sideload the apk to try and use it. OpenGL ES 2.0 on Instagram is used for its filters and I wonder if you refrain from using the filters, you could still use it? :-\
"the Transform's S3C6410 processor doesn't support hardware acceleration for OpenGL." via Engadget (
Samsung Transform review -- Engadget ).:-\