You could try messaging them and see if you could work together, couldn't hurt to ask at least.
For energy, there is a way to convert credits into energy via ports at a 2:1 ratio. 1 billion credits can bring 500 million energy which can be used in the alliance for offense, defense, or ship upgrades. Exploring for credits, collecting port interest, planet res, etc can build up energy pretty quickly if done certain ways.
We need to take it this way. They bought around 100 Billion Credits. Thats the amount i earned playing this game 4 Months from only killing Rebels.
I still have the problem with Adblocker http://prntscr.com/gxgr8h
If they decline because you attacked them previously then you could try other players and see if they will join up and help. The old saying, the enemy of my enemy is my friend, could come into play here. A new alliance friend/enemy/neutral feature may be coming soon to alliances near you in a future update that would allow alliances to form between alliances as well as the option to send each other resources and drones.
For ad blocker, have you tried clearing your cookies and cache? If you have then one of your plugins is calling a special javascript file on the server which in turn triggers a series of unfortunate events resulting in that message being displayed. Once the game no longer detects the special javascript file then it will disable that message.