Oh I'm glad to hear that. Yh I've also been looking for some PvZ clones and yeah they're hard to find so I just tried my best to create smth similar to the first level as I was kind of surprised almost nobody did something similar (at least the uploading part). So yh. Creating games in GDevelop or Construct is quite easy but I'm using the first now because Construct limited a lot in a lot of things, mainly events, so I couldn't get my game to be too large. I wanted to make a tower defense game and yh that's why I decided to move. probably never coming back to Construct.
I probably can't teach you how to use GDevelop all by myself but first thing you need are sprites. You can't do anything without sprites. You probably will need a program to create your sprites, I use Piskel because it's online and I do pixel art (at least for my own games, I only used assets for the PvZ test ones), but if you want something fast and don't feel like an artist, you can just draw a square and give it a color. That would be enough (you can create a sprite by right-clicking on your scene and then choosing "Insert a New Object". If you cannot find the scene, click on "View" and then pick "Show Project Manager".
You should have a scene by default but if you don't there should be an option to add one. When you open it there are 2 pages, a screen page (I call it like that because there lies everything that will be seen by the player) and an events sheet, where you can make the sprites do the things you want them to. Basically you just pick a condition (basically conditions are the "if/when" of GDevelop/Construct) and choose the ones you like, and then you add actions (these basically say what will happen when all the conditions mentioned are met). And basically that's all you need to know, or the basics to make your game. This engines are quite intuitive and if you don't know how to do something, you can probably search it up on youtube or ask me directly, although I recommend you do the first one because as I said I'm kinda occupied in my own game so I may not answer too quickly but yh.
Hope this helps you!