How do I add empty space between 2 image blocks?

To insert space between 2 Image Blocks, you would need to add a text block. You can set the size of the textblock by adding line spacing.

However, the text block would need to contain some form of text in it so that the spacing is saved. Please follow the instructions given below:

1. Insert the Image Blocks within the document.
2. Drag and Drop the Text block between the image block.
3. Add a sample text within the Text Block. Then add line spacing to adjust the size of the text block.
   
4. Once the text is added, you would need to select the text and change the font color to transparent. You would need to select the options annotated in the screenshot below to make the text transparent. Once the same is done, your document would have spacing between images.