The base tile that you used must have been changed by the website I used to share the image. If you take a look at the last picture that I posted you can see that inside the large square, there are no lines.

https://ibb.co/mB0byVM


Thank you, guys!

I'll read all the posts again and try to figure out what I should do!

I knew that snapping the base tiles could work but I was trying to use a feature that's built-in (the repeating pattern option).