George Baldock's late piledriver gave the Dons all three points after Antony Kay's equaliser cancelled out the opening goal from Michael Smith.
The visitors are six points behind sixth-placed Peterborough, but Robinson is unconvinced his side would be able to cut it in the Championship should they manage to sneak into the play-offs and then win promotion at Wembley.
Robinson said: "We're a million miles away if I'm honest. I think structurally we are ready but for me to get this team to seventh is a magician's trick.
"I've not spent any money, sold nearly £5million worth of players and not bought a player, so to still be competing year in, year out, it's credit to some wonderful people around me.
"We came here to try and spoil the game in the first half with a negative game plan to get people behind the ball.
"We felt if we could see the first half through, not concede and frustrate the fans, then quality things would come in the second half.
"I don't think we're ready to go up, but I'm going to give it every ounce of effort."
Swindon opened the scoring after 19 minutes when Smith tapped home from close range after Alex Pritchard's swerving shot had rebounded into his path.
The Dons grabbed the equaliser in the 68th minute when Ben Reeves whipped in a corner that was powerfully nodded home by centre-half Kay.
The visitors snatched victory in stoppage time when Baldock picked out the top corner of the net with a stunning strike.
Robinson was delighted for Baldock, who has now scored two goals in his last three games, and joked about the manner of the match-winner's celebration.
He said: "George has waited three years for a goal and then two come along in quick succession, so he's on a hot streak at the moment.
"The best thing is that he's one of our own, but the next time he runs away from me in celebration I'm going to knock him out!"