Btw I would love to login, I registered weeks ago, still waiting for confirmation email...
Every extraction marker must have a unit near by in order to move across that bridge.
Send scout to lure those Atlases and destroy...
Park 4 units near 4 extraction markers again and move one or all remaining (except those 4) mechs to the final objective. When you finish that one you can move all your units freely, bridge wont be destroyed.