I can't figure out how to sign up

I go to “upgrade”. It goes to page where I select which upgrade I want. I click on “sign up” on the one I want. I go to page that asks me to set up an account. I have an account so I click on teeny tiny writing at bottom that asks if I already have an account. It brings me to page that asks me to click on appropriate button below. The only button is a coupon code. I don’t have a coupon code and so I click on it anyways and it brings me to the same page.

I just want to pay you and … I really don’t have time for this!

The last page I came to says:

Please check the details of your subscription below and click on the relevant button to complete the subscription.

… and there’s no relevant button other than the “coupon code”

I’m wondering if you are looking at a different interface to mine. To buy a subscription, I log in with my account at https://www.routexl.com, click on my name on the top menu, click “Manage subscriptions” under “ACCOUNT” to the right of the screen, then scroll down to the option I want. When I click the “Subscribe” button it takes me to the PayPal checkout page to pay. I have never seen an option to enter a coupon code…