[Canvas custom resizing creates a super narrow canvas, how do I customize the canvas size?]

Also, it all has to be done all at once it won't save until I have done them all to their specifications? 

[Canvas custom resizing creates a super narrow canvas, how do I customize the canvas size?]

Sadly yes, its for Tablets here is some screenshots of the requirements. I have been stuck at this for 6 months longer than it took to make the app.

[Canvas custom resizing creates a super narrow canvas, how do I customize the canvas size?]

Here is a screenshot. I need the image I am making to be of this size 320X3840 px. Its for Google Play Store. I can't figure it out. I used to run Adobe Illustrator but it won't run on my Windows 11. So I really need this to work. The image needs to be this size and will include text. So do I just resize the image and text ?

The white strip is my Canvas which is unworkable.