i don’t understand why i dont have all the components required on the thunkable website e.g barcode scanner, columns, rows,
When you create a new project, you have a choice to “try out the new version.” If you check that box, then you are using the newer Drag & Drop (DnD) interface. Rows and columns and a few other features don’t exist or have been replaced by other components in that interface. If you leave the box unchecked, then you are using the older Snap to Place (StP) interface that has those components.
In DnD, the barcode scanner is in the Camera drawer: