New versions of Chrome on Android are shipped with the default feature of blocking third party cookies. Removing this option will enable other ads network (including Google itself) to track your online activities. Signup's privacy friendly suggestion is to use browsers that comes with default Trackers removal like Mozilla Firefox.

Anyway in order to use Signup.cash on your Chrome android you need to follow this steps:

Open the hamburger menu on the top right side of the screen:

Click on Settings:

In the new windows, find "Site Settings" and click on it. In the that section, look for Cookies.

After you clicked on Cookies you can find the option to unblock third party cookies. Make sure you remove the checkbox for Block Third Party Cookies like below.

That's all! Now you can go back to the web app again, reload the page and everything should work well.