Append_url_parameters

I need to authenticate users with our backend Caspio database, so trying to pass parameters to Open URL. Using:

APPEND_URL_PARAMETERS(“https://mywebsite.com/html/login.html?cbr=498aaaaabbbbbcccccddddd”, { EM: appVars.email_address, PW: appVars.user_pswd})

Should return a URL something like:
https://mywebsite.com/html/login.html?cbr=498aaaaabbbbbcccccddddd&EM=email@gmail.com&PW=mypassword

But instead, it’s inserting a / between login.html and ?, like this:

https://mywebsite.com/html/login.html/?cbr=498aaaaabbbbbcccccddddd&EM=email@gmail.com&PW=mypassword

So the link goes to a 404 page instead.

Does anyone have any suggestions on how can I get rid of that extra / at the end of the URL?

Thanks.