Before signing up for any subscription service, create a proper Apple ID account (or edit to make it proper), with all the information as asked, including name, DoB, country (+state), a verified email address (respond to test message!), and a valid payment method that allows for automatic and periodical charges.
You are advised to activate two-factor authentication for your Apple ID (not sure if required for subscriptions). For you that probably means adding a trusted phone number to the account, to receive verification codes on when needed.
Once the account is active, then you can subscribe. Get Apple TV+ - Apple Support
On Android mobile, you may go to tv.apple.com to do so.
Try deleting website data (cookies) for the apple.com domain, if the browser keeps acting up for this site.