Storage problem when I install ubuntu mate 20.04 on my pi4

Hello

I write the image of ubuntu mate 20.04 64 bit (focal fossa) with pi imager for install mate on my pi4, the problem being that when I boot, after a while (when there is the installation of the package with the small rectangle, after the screenshot step

), a message appears telling me that I am running out of space then on the main partition of 5.34gb that I am unable to extend, and the package installation is not successful. (i have a sd card of 128go)

Do you have a solution to extend the main partition on my whole sd card and not be limited to 5gb? But what I find strange is that on some tutorials that I saw no one had this kind of problem, yet I followed the same method.

I thank you in advance

There must be some problem with the method you are using to write the image to SDCard. I've done this install at least 5 times on different cards with different capacities and no problem.
I use a different tool to load the image.
When it has been written and then booted, the root partition should be automatically expanded to the whole remainder of the card (after allowing for the boot partition).
Derek