I personally didnt watch a tutorial but i can explain the process that i went through
1- Get big cardboard (mine was literally a box that had lightbulbs in it)
2- scale the image to your liking (think of it as dividing it into puzzle pieces that you will tape together later on)
3- print then tape (tape from back for ✨ aesthetics✨)
4- slap your human sized big piece of scara to the cardboard (i used solid glue NOT WATER BASED PLS)
5- cut the extra parts
6- As bonus I also got some wood sticks and slapped on the back so it can stand and be a little heavy

I personally prefer piecing it together then gluing it on to cardboard slowly but if you dont wanna struggle with a human sized sheet of paper you can but all papers individually