First you need to download the modpack itself. You can get it here:
Modpack DownloadNext you will have to get a ".mrpack" compatible launcher.
Incase you don't have one already - GDLauncher should be a reliable option.
You can download it here:
GDLauncherFor this section I'll assume that you're using GDLauncher, however any other ".mrpack" compatible launchers should work just the same.
Download the correct installer from the website and install the program.
Log in with your Microsoft or Mojang account. This will likely prompt you to open a window in your browser and copy a code to the dedicated field.
The process from then on should be fairly straight forward.
Once you're successfully logged in, you'll be prompted to create a new "instance". If not, you can do it by clicking the "+ add instance" button on the main screen.
Now you need to go to "Import" and then "MRpack".
Find the "select a zip" button. Now you need to select the "HoverCraft-0.2.0.mrpack" file in your file explorer.
The last step is to tick the box next to "HoverCraft-0.2.0" and click "Begin import".
This will take a minute, but once it's done, you can simply start the game by selecting the grass icon bellow.
Enjoy :)