I can sign in from my Linux PC, using the Brave browser, with no problems, except ... that bl**dy Captcha thing! Most times, the images are so bad that it takes several attempts to get it to work.
I have found that sometimes, not always, if instead of logging in using the normal method, I link to an email that I have been sent that confirms the status of a previous order, the Captcha seems to be bypassed.
I don't normally use their phone app - just hate doing things on a small screen. However, if you want to collect free delivery tokens, etc, you have no choice in the matter.