Orient hold a 1-0 advantage after Saturday's FA Trophy semi-final first leg at Brisbane Road.
Now the National League leaders will make the trip to Shropshire this Saturday with more than 3,000 tickets already sold for the second leg.
And Cowan feels that, despite the National North Bucks losing in London, all the expectation is on Justin Edinburgh's team.
"There was no fear going into it and ultimately there is no pressure on us," said Cowan
“The expectation is on Orient and there is nothing for us to lose.
“We wanted the tie to still be alive and it is.
“We are excited to bring them back to our place and I trust my players to perform when needed and bring things over the line.”
The Bucks had chances of their own in the first leg with Andre Brown and Daniel Udoh having efforts saved and blocked along with Darryl Knights.
Cowan said he trusts his players to give more of the same going forward in the home tie in a bid to turn the clash around.
He added: “I think we can do more of the same going forward, and they need to trust themselves more.
“We will look at the game and see what we can do better next week.”
As well as their good run in the Trophy, the Bucks have also enjoyed a better-than-expected season in the league.
They currently occupy a play-off spot and Cowan insists the club should be setting their sights high.
"Without sounding arrogant, I said when I took the job these things are available,"he added.
"Maybe it has come a bit sooner than anticipated but there is no roof on what we wanted to do.
"We are not just happy with a semi, we don’t want it to end there. We want to push to get to Wembley.
"The supporters have re-engaged with the team and we have given them something to be proud of. I am fortunate to have seen it as a player and know it is achievable.
"We want more and more supporters to come down and the New Bucks Head has been a fortress.
"We can’t thank the supporters enough for trusting the process, it is what I aspired to do this season."