The League Two Pilgrims recovered from a two-goal deficit and almost claimed victory when Andres Gurrieri's last-minute shot crashed against a post.
Adams said: "We are lucky, lucky people to be still in the competition. I won't sugar-coat anything because that was a very poor performance.
"We talked at half-time about maintaining the tempo from the start of the second half but that didn't happen because we were poor from the first minute.
"Our defending for both of Plymouth's goals was shocking. We dropped deeper and deeper when we should have been squeezing up the pitch.
"We allowed the pitch to get bigger and wider because we were so deep and then we couldn't hold the ball up front and didn't pass it well enough in midfield.
"I'm not going to complain about a Tuesday night replay at Plymouth because we are lucky to have a replay. We will have to play much better down there if we are to go through."
- Sports & Recreation
- Andres Gurrieri