If you need to produce a .png image file as a result of your work (for use/input to another application) then you need to Export it as a .png file.
Since you’re opening a .png file (the body template/map) and then adding layers as part of the image construction effort, you really need to Save it as a .kra file. If you don’t save it as a .kra file then you’ll throw away all the work you did with the layers.
You should always save as a .kra file to preserve the structure of your work and then later you can pump it out (Export it) as any other image file format you like .png, .jpg, .gif. etc.
If you’ve used GIMP before then didn’t you save multi-layer images as .xcf files?
Your screenshot does not include the status bar at the bottom of the window. This has information on it which can be useful in figuring out what problems may be.
Since you’ve turned off the visibility of the body template, I’m not sure why its grid lines are still visible.
Did you make Layer 4 using ‘New Layer From Visible’ after a right-click on the Damask layer (or via the Layer -> New menu)?
At some stage, did you use a layer blending mode that was not the Normal blending mode?
Where is the overall pink colour coming from? It’s not on the Damask layer or Layer 4 as far as I can tell from the layer thumbnails.
Can you provide the .kra file via a Dropbox or some file sharing link?