Town are welcoming Newark Flowserve to the Mike Riding Ground for an FA Vase fourth round match.
Victory would see Town progress into the last 16, having already won through five rounds to reach this stage and claimed more than £4,000 in prize money for doing so.
“We’ve done ever so well to get to the level we’re at,” said Ashcroft.
“It’s probably the biggest game in the club’s history, that’s how important it is to me.
“We are at home and I’d really like the people of Longridge to get behind us.
“I know Preston North End are playing at Blackburn on Saturday but any extra support we get would be great.
“It’s a one-off game and who knows what will happen?
“We’ve had a decent run in the FA Cup and we’ve made some money in this competition, which just helps us go along.
“We’ve gone from being a little club to where we are now in a short space of time.”
It will be a step into the unknown for Longridge given their minimal knowledge of Saturday’s opponents.
Similarly to Town, Newark Flowserve have had a good league campaign to date and are well placed in the Midland Football League Premier Division at the midway point of their campaign.
“All these teams from now on will be very good,” Ashcroft said.
“They will be a good test on Saturday, they are doing well in their league.
“We aren’t at a level where I can send scouts and it’s too far for me to go with working, but I’ve seen them on YouTube and had reports from managers I know down there.
“We’ll go into it pretty much blind so whether that’s a good or a bad thing, I don’t know, but it could be the same for them.”
However, Town will go into the game a man down after seeing midfielder George Thomason join Bolton Wanderers.
The 18-year-old has joined the League One club after featuring 26 times for Longridge this season, scoring two goals.
“It’s a childhood dream,” Thomason told the Bolton website.
“Becoming a professional footballer at a huge club like this is unbelievable and I’m buzzing to just kick on and get going and play for this great club.”