Nice to see a new map maker! You have a few issues but we'll work them out
Currently, the main issues is your map attachment is in .ld format not.pdb.
Your map must be in .pdb format to be downloadable and playable in the game.
To put your map in .pdb format:
Open your map(s) in M.exe
Click 'file' and then click 'export mission pack...'
You may need to fix errors that will cause you map(s) not to export
Upload your exported .pdb file in place of your current .ld file
Feel free to ask if you have any questions.