If you're planning on returning to the May Day event in 2021, keep in mind that the maze will be different this year, with a new puzzle to solve and a bonus package of Bell Vouchers to win. We'll get straight to the answer here, but if you haven't been to the Maze island yet, the next section will clarify how to get there. You can get new ACNH items as the rewards this year.
Gather the Shovel, equip it, and dig up the hedge that is blocking your path to the fruit.
You'll gain the power to dig up whole trees or break rocks if you eat the fruit. Let's go ahead and dig up the tree to the north.
Pick up the two pieces of wood here, then go east to the end and pick up the two pieces of fruit.
Now turn west and dig up the hedge past the entrance. There's some wood and a ladder recipe at the top.
Eat two pieces of fruit and use them to break the rock to the north, then go east and back west to dig up the tree.
Fill in the hole, then go south to get two pieces of fruit.
Continue north, but don't break the rock just yet. A workbench can be found to the west. We've now retrieved the same amount of fruit we had before joining this section of the maze, while also gaining access to the workbench. However, we don't yet have the tools to craft anything, so let's go out and get them.
Return east and eat two pieces of fruit, which will allow you to break the rock and dig up the three, each with a piece of fruit.
Eat this fruit as well to cross the gap to the north and plant a new crop.
Three pieces of wood (one to the south-west and three to the north-east) and a piece of fruit can be found in this section. Both of these should be taken.
Don't go any further just yet. Go back to your workbench. Two pieces of wood are still required for the ladder, which we can obtain by eating the fruit we just picked, smashing the rock, and heading north. At the workbench, make the Ladder.
Using the Ladder to climb up the platform to the south, where the Worn Axe can be found.
Return to the east, using the three holes as a guide. Using the Worn Axe on the tree after jumping over the middle hole going right to left. After this one use, it will split. You can now hop and slide over the tree stump.
To get the two pieces of fruit, use the ladder to reach the cliff below.
Return to the three holes and hop from one to the other from south to north to a tree. Dig up the tree with a slice of fruit, and use the shovel to dig up the two hedges here as well. You can now reach Rover using the ladder.
You are free to finish, however you can find that you have an extra piece of fruit. This is to assist you in obtaining some optional Bell Vouchers, which are worth picking up as a bonus.
To do so, use your ladder to descend the cliff on the left, dig up the hedge, and catch the four Bell Vouchers to the south.
Head north and west around the maze's perimeter before you come across a rock that is blocking two pieces of fruit. Consume your single fruit for the rock in exchange for two more.
Continue south around the maze's perimeter to find the remaining Bell Vouchers hidden behind three rocks. If you eat the fruit and break them, you'll be missing one and won't be able to get the remaining Vouchers.
Instead, go north and return to the workbench. There are two trees here that you can dig up with your fruit. A cliff with three pieces of fruit is beyond them, which you can hit with your Ladder.
Return to the maze's southern entrance and eat the three pieces of fruit to break the three rocks and obtain the Bell Vouchers.
We've completed our mission! Return to Rover right now to finish the maze. You will be given a Briefcase if this is your first time. Rover will be pleased to see you again if you completed it last year, and will post on your reward (which is - spoilers - a picture of Rover).